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MACMILLAN & CO., Limited 





, ' AS 




director of the observatory at flagstaff, arizona; non-resident professor 
of astronomy at the massachusetts institute of technology; fellow of 
the american academy of arts and sciences; membre de la society 
astronomique de france; member of the astronomical and astro- 
physical society of america; mitglied der astronomische ge- 
sellschaft; membre de la societe belge d'astronomie; 
honorary member of the sociedad astronomica de mex- 
ico; janssen medalist of the societe astronomique de 
france, 1904, for researches on mars; etc., etc. 


'Nz^ gork 


u4/I rights reserved 

o^ \^ 


Two Ooo'es Received 

DEC 14 1908 

cuss 0C» XXc s^o, 

Copyright, 1908, 

Set up and electrotyped. Published December, 1908. 

J. 8. Gushing Co. — Berwick & Smith Co. 
ISTorwood, Mass.. U.S.A. 











In 1906 Professor Lowell was asked by the trustee 
of the Lowell Institute to deliver a course of lectures 
there upon the planet Mars. Eleven years had elapsed 
since, at the invitation of the former trustee, he had 
done the like. When the time came for their delivery 
unusual interest was manifested, the course proving 
the most thronged of any ever given before the Insti- 
tute. So great was the demand for seats that the hall 
could not contain the crowd, and the lectures had to 
be repeated in the afternoons, to audiences almost as 

The eight lectures were then published, with slight 
changes, in six papers in the Century Magazine^ and 
were subsequently wanted by Macmillan and Com- 
pany for issuance in book form. 

Though dealing specifically with Mars, the theme 
of the lectures was that of planetary evolution in gen- 
eral, and this book is thus a presentation of something 
which Professor Lowell has long had in mind and of 
which his studies of Mars form but a part, the re- 
search into the genesis and development of what we 
call a world ; not the mere aggregating of matter, but 


what that aggregation inevitably brings forth. The 
subject which Hnks the Nebular Hypothesis to the 
Darwinian theory, bridging the evolutionary gap be- 
tween the two, he has called planetology, thus desig- 
nating the history of the planet's individual career. 
It is in this light that Mars is here regarded : how it 
came to be what it is and how it came to differ from 
the Earth in the process. 

The object of the founding of the Observatory at 
Flagstaff was the study of the planets of our solar 
system ; a subject it has now for fourteen years made 
its specialty, the site, chosen for the purpose, en- 
abling it to prosecute this study to more advantage 
than is possible at any other observatory at present. 
From the data thus collected, light has been thrown 
upon the evolution of the planets as worlds, resulting 
in a thesis of which the present book is a preliminary 

As in all theses, the cogency of the conclusion hangs 
upon the validity of each step in the argument. It is 
vital that each of these should be based on all that 
we know of natural laws and the general principles 
underlying them. Their truth can only be adequately 
appreciated by those able to follow the physical and 
mathematical processes involved, and for this the gen- 
eral reader has not the necessary technical education. 
Yet there are many, professional and unprofessional 


alike, capable of comprehending provided the steps 
are made sufficiently explicit. It has seemed, there- 
fore, worth the trying to attempt to write for both 
classes of the community in a single volume. To do 
this, the general text has been printed complete in 
itself, while the demonstrations of the several steps 
have been collected in a part by themselves with refer- 
ence to the places in the text where they severally 
should occur. All illustrations of the planet Mars 
are by Professor Lowell. 

May, 1908. 






I. The Genesis of a World .... 


Catastrophic origin ...... 


Meteorites ....... 


Meteorite worship . . . . . . 


Meteoric constitution of solar system 


Analogy of cataclysm to new stars (Novae) 


The meteorites gravitate together, generating heat 


Amount of heat depends on the mass of the body 


' Substances vary with heat and pressure . 


^ Mass the fundamental factor .... 


Cooling . . . . . 


Life-history depends on size .... 


Planetologic eras ..... 


Present aspects of the planets our guide . 


Geologic part of planetology .... 


Landscape the result of cooling 

. 14 

Mountains in proportion to mass 

. 15 

Volcanic phenomena ..... 

. 16 

Relative roughness of Earth, Moon, and Mars . 

. 16 

Mountains absent on Mars . 


Slant illumination ..... 

• 17 

Importance to astronomers .... 

• 17 

Applied to Mars . . . . . 


Not indicative of mountains .... 


Two or three thousand feet limit of elevation on Mars 





Internal heat of the three bodies 

Darwinian theory of lunar origin 

Confirmed by lunar surface . 

Probable comparative internal heat of earth and 

Continental and oceanic areas formed 

Their distribution determined 

True Martian message 

Their relative size on different planets 

Earth's oceanic basins permanent . 

Their flooring attests it . . . 

II. The Evolution of Life 
The origin of organic life 
Life an inevitable phase of planetary evolution 
Water essential to life .... 
Seas the earliest home of mundane life 
Uniformity of paleozoic fossils 
Carboniferous plant life 
Light less and heat more then than now . 
Effect on the earth .... 
Earth itself responsible for paleozoic heat . 
Earth, not sun, the motive force in evolution 

paleozoic era . 
A once cloudy Mars .... 
Life outgrows the sea . 
Effect of environment upon evolution 
Deep-sea life thought impossible fifty years ago 
Extinction of light 
Deep-sea life 

Blindness .... 
Phosphorescent organs . 
Lesson of the fishing fishes 
Cosmic character of life 

III. The Sun Dominant 



in the 




One species supplants all others .... 206 

To die of thirst .... 


End foreseen .... 


Further phenomena 

21 1 

Speculation excluded . 


Our hfe not unique 


Martian life nearing its end . 















On Moment of Momentum .... 

The Connection of Meteorites with the Solar System 

The Heat developed by Planetary Contraction 

The Heights of Mountains on the Moon 

Heat acquired by the Moon 

Surface Heat of Mars 

The Boiling-point of Water on Mars . 

The Paleozoic Sun .... 

EiFect on the Earth of the Supposed Paleozoic Sun . 

On the Influence upon the Climate of Carbon Dioxide 

the Air .... 
Atmosphere of Mars 
The Mean Temperature of Mars 
A Dust Storm on Mars 
Mars on the Cause of an Ice-age 
Tidal Effects .... 
On the Visibility of Fine Lines . 
Canals of Mars 
Position of the Axis of Mars 

Index . 






I. On the Road to the Observatory 



II. Mars — 1905 

III. Spectrogram of Moon and Mars showing the Water- 

vapor Band ...... 

IV. Tw^o Photographs of London taken from a Balloon 
V. At the Telescope — Observing Artificial Planets 

VI. The Lov^ell Observatory in Mexico 

VII. Mars in 1905 . . . . . " , 

VIII. A Chinese Translation of Lov^ell's ** Mars'* 





Morehouse Comet ....... 

Meteorite from Canon Diablo, Arizona (pitted by fusion) 
Meteorite from Canon Diablo, Arizona (surface polished) 
Cloud Effect on Jupiter ..... 

An Apple shrunk to show the Effect of Contraction 
Phase View of the Moon, Mountainous Surface on the Termi 
nator ....... 

Phase View of Mars, May, 1907 

View of the Earth for Proportion of Land and Sea 

Dust Storm on Mars ..... 

Two Views of the Earth as seen from Space 

Two Views of Mars for Comparison with the Earth 

A Part of the Moon's Face showing Ancient Sea-bottoms 

View of Mars apportioning Dark and Light Areas . 

View of the Moon at the Full, in Like Manner 








Model of a Brontosaurus ...... 

Plant Life in the Coal Measures — from a Fossil Specimen 
Plant Life of the Upper Devonian — from a Fossil Specimen 

A Trilobite 

Fossil Footprints of Amphibia 

Deep-sea Fishes ; Challenger Expedition 

Deep-sea Fish ; Challenger Expedition 

Deep-sea Angler Fish ; Challenger Expedition 

Deep-sea Fish ; Challenger Expedition 

Two Views of the SoHs Lacus Region on Mars, One Hour Apar 

The North Polar Cap of Mars at its Least Extent . 

The South Polar Cap of Mars at its Greatest Extent 

Drawing of Mars with Dark Belt girdling Snow during its Melting 

Early Winter Snow Storm in the Northern Hemisphere of Mars 

Merriam's Map of the San Francisco Mountain and Vicinity 

The San Francisco Peaks . . . . ' . 

Arizona Desert View ...... 

The Douglas Fir ....... 

Vertical Distribution of Climate on Mountains, showing how 

Land-masses raise Temperature . 
Diagrammatic Profile of the San Francisco and O'Leary Peaks 

from Southwest to Northeast .... 
Chart of Effect of Plateau on Tree Zones — Less Elevation 
Chart of Effect of Plateau on Tree Zones — Greater Elevation 
Diagrams of Two Craters with Axis of Greatest Cold N.N. W 
Comparative Sizes of the Earth and Mars with the Polar Caps 

of Both in their Springtime 
Lines in the Dark Areas of Mars, proving that the Latter are 

not Seas ...... 

Two Views of Mars with Parings on the Terminator 

Map of North America, showing approximately the Area of Dry 

Land at the Close of Archaean Time . 
Petrified Forest of Arizona ..... 

Another View of the Petrified Forest of Arizona 
Effect of the Spring Mist around the North Polar Cap of Mars 



A Section of the Canal Eumenides-Oicus terminating in the 

Junction Trivium Charontis 
Canals in Dark Regions connecting with the Polar Cap 
Camera of the Lowell Observatory by which the Canals of Mars 

were Photographed .... 
Ascraeus Lucus, from which radiate Many Canals 
Single and Double Canals 
A Mass of Double Canals 
A Mass of Single Canals about Lucus Phoenicis 
Cartouche of the Ceraunius — from a Chart by Lowell . 
Time of Vegetation on the Earth — from a Chart by Lowell 
Sprouting Time of Vegetation on Mars — from a Chart by Lowell 
Luci Ismenii, revealing the Systematic Method in which the 

Double Canals enter the Twin Oases .... 
The Moon, showing the Straight Wall and Rill to Right of Birt 

— from a Drawing by Lowell, May, 1905 . 
Mercury — Drawings depicting the Irregular Character of the 

Lines on the Planet differing entirely in Look from those on 


A Corner of Mars, June 10, 1907 

Arethusa Lucus, April 15, 1903, with Converging Canals from 

the North Polar Cap 
Canals from the South Polar Cap of Mars 
Djihoun ...... 

Differentiation of the Ganges 

Northeast Corner of Aeria, July 2-5, 1907 , 

The Carets of Mars .... 

Mouths of Euphrates and Phison . • 












UP to the middle of the nineteenth century, astron- 
omy was busied with motions. The wanderings 
of the planets in their courses attracted attention, and 
held thought to the practical exclusion of all else con- 
cerning them. It was to problems of this character 
that the great names of the past — Newton, Huygens, 
Laplace — were linked. But when the century that 
has gone was halfway through its course, a change 
came over the spirit of the investigation; with the 
advance in physics celestial searchers began to con- 
cern themselves with matter, too. Gravitational as- 
tronomy had regarded the planets from the point of 
view of how they act ; physical astronomy is intent 
upon what they are. 

One outcome of this more intimate acquaintance 
is the new study with which the present papers deal : 
the evolution of the planets regarded as worlds. Such 
research has to do not merely with the aggregation 
of material, but with its subsequent metamorphoses 


after it has come together. Planetology we may call 
this science of the making of worlds, since it concerns 
itself with the life-history of planetary bodies from 
their chemically inert beginning to their final inert 
end. It constitutes the connecting link in the long 
chain of evolution from nebular hypotheses to the 
Darwinian theory. It is itself neither the one nor 
the other, but takes up the tale where the one leaves 
off, and leaves it for the other to continue. 



SO far as thought may peer into the past, the epic Catastrophic 
of our solar system began with a great catastrophe. °"^'"' 
Two suns met. What had been, ceased ; what was 
to be, arose. Fatal to both progenitors, the event 
dated a stupendous cosmic birth. 

It is more than likely that one or both of the col- 
liding masses were dark bodies, dead suns, such as 
now circle unseen in space amid the bright ones 
we call the stars. Probable this is, for the same 
reason that the men who have been far outnumber 
the men who are. It is not to be supposed that the 
two rovers actually struck, the chances being against 
so head-on an encounter ; but the effect was as dis- 
astrous. Tides raised in each by the approach tore 
both to fragments, the ruptured visitant passing on 
and leaving a dismembered body behind in lieu of 
what had been the other. That the stranger con- 
tinued on its way is shown by the present moment of 
momentum of our system. For it is very small, and 
the fact can be proved to mean that after the encoun- 
ter its matter still lay massed for the most part in a 





single centre.^ Thus, what had been a sun was left 
alone, with its wreckage strewn about it. Masses 
large and small made up its outlying fragments, scat- 
tered through space in its vicinity, while a shattered 
nucleus did it for core. So much of its history we 
learn from the tiniest of its constituents now: the 
meteorites. To meteorites thus attaches a peculiar 
importance ; for they are Rosetta stones for the de- 
cipherment of what went before. 

From time unreckoned, rocks have fallen out of 
the sky upon the Earth. Most of them are of stone, 
but some are nearly pure iron, mixed with a small 
amount of nickel. They are called meteorites. 
Twenty-six known elements have been found to occur 
in them, and not one element that is new. They 
thus betray a constitution cognate to the Earth's. 

In size these visitants vary from the grain-like 
bodies known as shooting-stars up to ponderous 
masses weighing many tons. Coming from space, 
they enter our air at speeds of from eleven to forty- 
one miles a second, and friction, due to their great 
velocities, fuses their exterior, and eats the holes with 
which is pitted what remains of them when they strike 
the ground. 

Recorded meteoric falls date from a far past, and 
were deemed miraculous by early men. A stone that 
fell in Phrygia in pristine times was adored as Cybele, 


" the mother of the gods," and later, about 204 B.C., 
was carted with great ceremony to Rome. The fa- 
mous Diana of the Ephesians was probably none other 
than a meteoric stone, enshrined and worshipped as 
a goddess. Adoration of such arrivals from heaven 
was not of local observance only, but common to 
peoples over the whole Earth. There was a stone so 
worshipped at Mecca, and another in Tatar, Siberia, 
to which homage was paid ; while even in our own 
country a large mass of iron found in Wichita County, 
Texas, was set up as a fetich by the Indians, who re- 
vered it as a body not of the Earth, but sent to it 
by the Great Spirit. 

A certain poetic justice invests this worship with a Meteoric 

1 r ' r ^ i • i i i i constitution 

grandeur or its own ; tor these thmgs are probably the ^^^^^^^ 
oldest bits of matter we may ever touch, the material system. 
from which our whole solar system was fashioned. 
They mark the farthest point in its history to which 
we can now mount back. The time of day at which 
they commonly fall — the afternoon rather than the 
morning — points curiously to their oneness with 
the rest of the solar system ; for in the afternoon the 
Earth looks backward over its traversed path, and 
their descent then proves that they follow and over- 
take it, and therefore that their movement has the 
same sense as its own. Still more conclusive of their 
relationship to ourselves is the speed with which they 


arrive, or, to be precise, the lack of it. For, did they 
come from the depths of space, were they ronins of the 
sky owing attraction's allegiance to no one lordly sun, 
they would have velocities exceeding forty-five miles a 
second, and these should often show, not an instance 
of which has ever been remarked.^ 

Just as, chemically and gravitationally, they stand 
confessed our kith and kin, so, physically, they betray 
the character of their origin; for they. bear in them 
occluded gases, which could have come there only 
under great pressure, such as would exist in the inte- 
rior of a giant sun. Thus they proclaim themselves 
clearly fragments of some greater body. To the some- 
time dismemberment of this orb, from which disinte- 
gration our sun and planets were formed, the little, 
solitary bits of rock thus mutely witness. 

Of the cataclysm that thus occurred far down the 
otherwise unrecorded vista of time, we have an ana- 
logue in the Novae that now and then blaze forth in 
the sky to-day, startling us from out the depths of 
space. These new stars, that suddenly appear, grow 
in brightness, and then slowly fade to nebulosity, 
speak by such action of a like catastrophe by which 
they were born again. Not otherwise was our own 
The meteor- ^'^^^^ hcraldcd in heaven. 

ites gravitate 

together, Strcwn thus about the scene of the encounter, the 

heat^^ " pieces of the disrupted sun would begin to gravitate 

Analogy of 
cataclysm to 
new stars 


together. The several subsidiary swarms of these 
fragments were of different sizes, but of much the 
same substance, because of the general similarity of 
their origin. 
Cooled by 
contact with 
the cold of 
space, so soon 
as the meteor- 
ites started to 
fall together, 
they gener- 
at ed heat, 
warming one 
another, just 
as the rubbing 
of two sticks 
strikes fire. 

The amount The Morehouse Comet as photographed at the 

f, , Lowell Observatory, 1908 

of heat pro- By E. C. Slipher. 

duced depended upon the number of particles con- 
cerned, or, in other words, upon the mass of the body 
the particles were busied to form. 

Approximately we can compute what this heat would Amount of 
be. If the body be supposed homogeneous, and to "j^the^mass^ 
contract under its own gravity from an original ex- of the body. 
tended condition to an eventually compressed state, 



vary with 
heat and 

the work done, converted into heat, would be propor- 
tionate to the square of the mass divided by the radius 
attained. The same would be the case if the body 
were heterogeneous and composed of concentric spher- 
ical shells, only that the numerical amount would be 
greater according to the distribution of the mass. 
However the body were constituted, its caloric would 
be spread through the mass, and the resulting heat on 
each unit of it would therefore be as its mass divided 
by its radius. The internal temperature of the par- 
ticular planet would therefore depend upon the 
amount of material that collected together. Thus 
each body was subjected to a different heat as well as 
to a differing pressure, according to its mass from the 
moment it began to form ; and to its mass alone, for 
that determined the radius to which it finally stood 
compressed.^ ' 

Now, all substances behave differently according to 
the temperature and the pressure under which they 
exist, both as to physical state and in their display of 
chemical action. Diverse results ensue from diverse 
conditions. The same element melts or remains solid, 
combines with another eagerly to form a third utterly 
unlike both, or coldly stands aloof from all association, 
solely as the temperature or the pressure constrains it 
to that end. Each, too, is a law unto itself, and acts 
unlike its neighbor as these compelHng causes change. 


To them, therefore, diversity is due ; and they in their 
turn are conditioned by the mass. 

Mass, then, is the fundamental factor in the whole Mass the 
evolutionary process, the determining departure-point, ^"^^'"'^"^^^ 
fixing what the subsequent development shall be. 
Though the bodies were in essence the same at the 
start, their initial quantity would change their very 
quality as time went on. What started like would 
become different ; for the gathering together of the 
particles into a single body was the preface to that 
body's planetary career. 

Not until the internal heat began to abate did what 
we call evolution set in. Up to then the growing 
temperature induced a devolution or separating into 
simplicity of what had been complex. The time taken 
by each planet to reach its maximum bodily heat 
differed as between one and another. The larger the 
body, the slower it attained the greatest temperature of 
which it was capable, both by reason directly of its 
mass, and indirectly of the pressure to which that mass 
gave rise. 

At its heat-acme the picture each planet presented Cooling. 
was all its own. Some may have been white-hot, 
some certainly were red-hot, some were merely darkly 
warm ; for one differed from another in self-endowment 
of warmth or light, each with a glory of its own. 

Radiation had, of course, been going on from the 


time the impact of the particles began. At first the 
heat gained by contraction surpassed that radiated 

away, but at last a 
time came when the 
depletion exceeded the 
generation of heat, and 
the planet began to 
cool. By parting with 
its caloric into space, 
its surface fell in tem- 
perature. Unlike in 
amount of acquisi- 
tion, the bodies were 
no less unlike in the 
manner of their loss. 
Each acted according 
to its kind. Those 
'^^^^^m^^^' . that originally had lit- 

tle, lost that little fast ; 
for volume is a matter 

Meteorite from Canon Diablo, Arizona 

■D-,,Au r • • . • .1, .u> of three dimensions, 

ritted by fusion m traversing the earth s 

atmosphere. SUrface of but tWO, 

and as through their surfaces their volumes cooled, 
the smaller got rid of their heat with relatively 
greater speed. Just as if two stones be put 
into the fire and then taken out, the smaller will 
turn cold while the larger is yet warm. With the 



depends on 

planets, contrast in performance was accentuated from 
the fact that the big ones were intrinsically hotter at 
the start. Thus, for two reasons, the large Hngered 
in the race : they had more to lose, and they lost it 
more reluctantly. 

In consequence the life-history of a planet was long Life-history 
or short in proportion to its size. If little, it ran 
through its gamut of change fast, and that gamut was 
itself brief; if large, it tarried in its several stages, 
and those stages were themselves drawn out. But, in 
addition to this, the larger knew states the smaller 
in their heating had never reached. Diversified age, 
both in length of years and in breadth of experience, 
was thus the first 
result of size. 

Six stages may 
conveniently be dis- 
tinguished in the 
progress of a planet 
from sun to cinder, 
all of which will be 
traversed by the 
body, if it be suffi- 
ciently big. If it be 
of asteroidal size, it 

virtually knows none of them, remaining meteoric from 
first to last. The six periods may be designated : — 










Meteorite from Canon Diablo, Arizona 
Surface polished. Showing method of 


I. The Sun Stage. Hot enough to emit light. 
II. The Molten Stage. Hot, but lightless. 
III. The Solidifying Stage. Solid surface formed. 
Ocean basins determined. Age of Metamor- 
phic rocks. 
IV. The Terraqueous Stage. Age of sedimentary 

V. The Terrestrial Stage. Oceans have disappeared. 
VI. The Dead Stage. Air has departed. 

Present Though wc cannot in our own ephemeral life watch 

aspects of the , 111 11 r • 

planets our ^^7 pl^^^t pass through thcse several phases or its 
s"^^^- y^^ ^"\ career, we can get a view of the 

process by studying the present 
conditions of the various planets 
and piecing together the informa- 
tion we thus obtain. It is, in the 
Cloud^e^cton end, as conclusive as in botany 
Jupiter would be the studv of a wood 

As observed at the I.owell 

observatory in 1907, by Carefully noting the condition 

indicating that Jupiter r r\ * j • • j 1 ^ • ^u • 

. . ^^ J 1 . or the mdividual trees m their 

IS m the second planeto- 

logic stage. various growths from seedling 

to patriarch. Thus, at the present moment, in Stage 
II are found Neptune, Uranus, Saturn, and Jupiter; 
in Stage IV, the Earth; in Stage V, Mars; and in 
Stage VI, the Moon and the larger satellites of the 
other planets. 


Each planet's internal heat was its initial motive- 
power, and cooling the mode by which this energy 
worked, first, to the fashioning of its surface, and then 
to all evolution upon it. While still in the molten 
state the mass was a seething chaos but little differen- 
tiated from any other equal agglomeration of matter. 
Yet even here the several substances had begun to 
segregate, the heavier falling to the bottom, the lighter 
rising to the top. 

With Stage III we enter the part of a planet's Geologic 
career with which, on our Earth, geology is concerned. ^^,^ ° , 

■' -'00-' planetology. 

Though specifically the story only of our Earth, that 
science has analogues elsewhere, and to be best under- 
stood needs to be generically considered. Local as 
many Earth-happenings are, with increasing light from 
the heavens it is becoming clear that the main events 
are of cosmic occasioning, and that astronomic cause 
presides over their manifestations. Initial instance of 
planetary action occurs at the first stage of the Earth's 
history to which geology mounts back — that in which 
a crust began to form over the molten mass. The liq- 
uid metal in a furnace upon which the solidifying slag 
has begun to float gives us an idea of this early state 
of things. Our metamorphic rocks were in action 
akin to the furnace slag, rising to the surface because 
of their lightness. Proof of this lies in their present 
density, which is only about one-half of the average 


the result 
of cooling. 

density of the Earth, 2.7 times that of water instead of 
^.^. Their constitution furnishes further evidence 
that such they were. The gneiss, mica, and horn- 
blende of which they are composed show by their 
crystalline form that they cooled from a once molten 
state, and their foliation indicates that they were crum- 
pled and recrystallized in the process. 

In Stage III the body first acquires a physiognomy 
of its own. Up to then it is a chaotic mass as unstable: 
and shifting as clouds in the sky ; but at the advent of 
surface solidification its features take form — a form 
they are in fundamentals ever afterward to keep. Its 
face is then modelled once for all ; and its face is the 
expression of its character. Our knowledge of this 
stage and of the two subsequent stages IV and V is 
derived from study of three planets of our system; the 
Earth, the Moon, and Mars. The others contribute 
nothing to our information of these mid-phases, either- 
because, like Mercury and Venus, they are too ad- 
vanced, or because, like the major planets, Jupiter,, 
Saturn, Uranus, and Neptune, they are not advanced, 

Landscape is simply the sculpturing due the fash- 
ioning cause of planet physiognomy. As the sub- 
stances composing the mass cool, some of them expand ; 
but most of them contract, and in consequence of this 
the crust finds itself too large for what it encloses.^ 



To fit the shrunken kernel it must needs crumple 
into folds. These folds are what we know as moun- 
tain ranges — long, low swells while the crust is yet 
thin, abrupt and broken fractures when it has become 
thick. The valleys between mark the down-folds 
of the squeeze. 
Wrinkles are 
thus as inevitable 
a consequence of 
planetary aging 
as of man's, only 
that while they 
are thought a 
disfigurement in 
him, they are re- 
garded as beauti- 
ful in a world. 

Such crinkling 
of its cuticle is 
most pronounced 
where the heat to 
be got rid of is 
greatest, and the surface to radiate it is relatively 
least. Both conditions are fulfilled the more com- 
pletely the bigger the body. The larger the planet, 
therefore, the more mountainous its surface will be 
when it reaches the crumphng stage of its career. 

An Apple, shrunk to show the Effect of 

Mountains in 
proportion to 


Volcanic j^ Hke manner is volcanic action relatively increased, 


and volcanoes arise, violent and widespread, in pro- 
portion ; since these are vents by which the molten 
matter under pressure within finds exit abroad. This 
is shown in their positioning. They occur where the 
crust is most permeable, and so are found along the 
edges of continents, as these are weakened by dipping 
down into the sea. 
Relative Three bodies exist near us in space where the work- 

Earth Moon ^"g ^^ ^^^^ inevitable action stands displayed, and its 
and Mars. Comparative effects may thus be studied : the Earth, 
Mars, and the Moon. With the accidented character 
of the Earth's surface we are all famihar. Its moun- 
tains, its volcanoes, and its hills go to make up its 
loveliest and its grandest features. Its mass fashioned 
them, and fashioned them as they are because its mass 
was large. This mass is nine times that of Mars, and 
eighty-one times that of the Moon. Being greater 
than that of the Moon or Mars, our globe should 
have crumpled more, and those other two bodies 
should have smoother contours than the Earth shows. 
The general order of their roughness should be 
Earth, Mars, Moon. 
No mountains Now, whcn wc comc to scan Mars with nicety, we 

on Mars. in i r • t • r ' 

^TQ gradually made aware or a curious condition or its 
surface. It proves singularly devoid of irregularity. 
The more minutely it is viewed, the more its level- 


ness grows apparent. Finally, calculation shows that i 

heights, even of very moderate elevation, should be j 

visibleif such existed, and none show. Thus we are con- - 

fronted by the fact that there are no mountains on Mars. 

Second only in interest to the fact itself is the slant 
method by which that fact has been found out. To ' """'"^'^'°"- i 
appreciate the problem, we may recall the appearance 
of a road lighted by electric arc-lights placed at such l 

considerable distances apart that the illumination falls 
aslant. All of us who, on dark nights in the country, ; 

have trudged along such pikes, have started at the ; 

mammoth sharp-cut shadows of its ruts, so that we i 

have lifted our feet to surmount what threatened to ; 

stub our toes, only to find the obstacles not there. ■ 

To such delusion were we led by the monstrous ! 

length of the shadows thrown with unexpected vivid- 
ness across our path. 

Now, the fact of such projection, — as Cowper puts important to 
it of his legs under the rays of a rising or a setting ^^'^'^°"°'"^'^^- j 
sun, "spindling into longitude immense," — bother- \ 

ing as it is to the midnight pedestrian on arc-lit roads, ., 

proves to the astronomer of inestimable use. For 
without its aid he had forever remained incapable of 
gaging the inequalities of the terrene of the heavenly- 
bodies to any fine precision. 

When an object stands on the sunrise, or the sun- i 

set, edge of a planet, the slant illumination it then ] 

C ! 


receives throws its shadows to a great distance from 
its foot. A tapering finger searching the plains as 
the sun changes position, it may be a hundredfold the 
height of the object casting it. The effect is well seen 
in photographs of the moon. 

Deprived of. this natural kind of magnification, the 
astronomer would be forced to measure the object 
itself for just what it was, as it showed in profile on 
the limb, the fully illuminated rim of the planet where 
the sight-line of the observer grazes horizontally the 
surface, and shows heights for just what they are. 
With shadows he has a vernier to his hand. For the 
derived may be any number of times longer than the 

On the same principle, by noting the distance off 
the general sun-lightened edge at which some fortunate 
N^^ peak first catches the rays of the rising sun, or holds 

latest his setting beams, its loftiness may be found.^ 

The principle has been employed to determine the 
heights of the mountains in the Moon. By the help 
of trigonometry the shadows and the star-like tips of 
peaks, standing isolate beyond the general edge of 
light, have been made to tell their tale of elevation. 
In consequence, we know the heights of crater walls 
there, to within a few hundred feet, as accurately almost 
as we know them on Earth by our aneroids. 

Applied to ■' 

Mars. The same procedure applied to Mars results in a 



negative outcome. While the sunrise or sunset edge 
of the Moon is palpably notched, even to the naked 
eye, as any one may see who scans it carefully a 

Phase View of the Moon, showing the Effp:ct of a Mountainous 
Surface on the Terminator (the Dividing Line between the 
Illuminated and the Obscujied Part of the Face) 

few days before or after the half, the similar edge of 
Mars is wonderfully smooth and even. One may 
gaze, armed with the most powerful glass, night after 
night, and never detect the least irregularity in its 


elliptic outline. Commonly, at most, he will notice 
slight flattenings here and there where a dark area 
happens at the moment to be passing over the boun- 
dary of sunlight and shade. So 
rare is it to perceive any other 
indentation or excrescence upon 
the smooth rim of its disk where 
the light fades away, that to do 
so is something of an astronomic 
event. The very rarity of the 

Phase View of Mars, ^ •' 

May, 1907, SHOWING phenomenon — there has been 

A Smooth TER^^NATOR , , i r 1 

(THE CURVED LiNE AT ^^^ one good onc at each of the 
THE Left), which in- j^st three oppositions — proves 


NO Mountains on the the projections not to be due to 
^^^^^^ what causes them on the Moon, 

an accidented surface. In short, they cannot indicate 
mountains, for a mountain is a permanence, which under 
similar conditions should either always or never show. 
Now, for many nights in succession, indeed for weeks 
together. Mars presents us his disk under substantially 
the same conditions night after night; so that if the 
obstacle that caught the light were part and parcel of 
the surface, however it might tower above that sur- 
face's customary level, it should be seen as regularly 
as the planet's rotation brought it round. The fact 
that it fails of such continuity of expression is proof 
conclusive that it is of no such origin. 



View of the Earth, showing the Proportion of Land and Sea 
Sporadicity, then, far from raising the slightest pre- Not indicative 

/» (^ . .... 1 . of mountains. 

sumption m ravor or mountams, or mdicatmg their 
uncommonness, is absolutely fatal to the observed 
phenomenon being a mountain at all. Now, as none 
of these projections seen on Mars are of permanent 
appearance, we perceive that there are no mountains 
on Mars. Such impermanence testifies not only neg- 
atively but positively to their character. For, from 
the fact that when detected two nights running they 
prove to have changed their place in the interval, we 


Two or three 
thousand feet 
limit of eleva- 
tion on Mars. 

have witness that they are unattached. Thus they 
come from something floating in the planet's air ; to 
wit, clouds, and, furthermore, from 
their color, clouds of dust. 

From the evidence as to scale 
afforded by the Moon, we can 
tell what height we ought to be 
able to detect in this manner on 
Mars. We find it by calculation 
to be two to three thousand feet. 
Nothing, therefore, higher than this modest elevation 
exists there, which leaves us for contemplation a sur- 
face singularly flat, according to the idea with which our 
Earth has furnished us. A Martian landscape would 

Dust Storm on Mars, 
FROM A Drawing, 
May 28, 1903 

From " Old and New Astronomy," by R. A, Proctor, Longmans, Green & Co. 

Two Views of the Earth, 180° apart, showing the Polar Caps and 
General Features as seen from Space 

seem to us remarkably peaceful and tame, — scenery 
chiefly noticeable for the lack of everything that with 
us goes to make it up. 

Contemplating now the Moon in the light of what 


we have thus learned, the first thought that strikes us 
is the glaring exception seemingly made by it to the 
theoretic order of smoothness, Earth, Mars, Moon, 
above laid down. The lunar surface is conspicuously 
rough, pitted with what are evidently volcanic cones 
of enormous girth and of great height, and seamed by 
ridges more than the equal of the Earth's in elevation. 

Two Views of Mars, about i8o° apart, showing the Polar Caps and 
General Features for Comparison with the Earth (as above) 

Many lunar craters have ramparts 17,000 feet high, 
and some exceed in diameter 100 miles; while the 
Leibnitz range of mountains, seen in profile on the 
lunar Umb, rises nearly 30,000 feet into space. 

On the principle that the internal heat to cause internal 
contraction was as the body's mass, — and no physical ^^ree bodies. 
deduction is sounder, — this state of things on the 
surface of our satellite is unaccountable. The Moon 
should have a surface like a frozen sea, and it shows 
one that surpasses the Earth's in shagginess. To per- 
ceive this more definitely we will make that not unin- 
teresting thing, an evaluation of the heat evolved by 


both the Moon and the Earth, supposing their origin 
the same. We will express it in terms, if not in fig- 
ures, that are comprehensible. The result is startling. 
Unaccountable at a first view, the event proves actually 
impossible when we subject the heat evolved by a like- 
genesis to numerical computation. If the Earth con- 
tracted homogeneously from an infinite expansion to its 
present state, and none of its heat were lost meanwhile 
by radiation, calculation shows that the energy evolved 
would be sufficient to raise the temperature of its en- 
tire mass to 146,000° F., if that mass were composed 
of iron, which represents about its present density and 
is probably not far from the fact. If it were com- 
posed of other material, the temperature of that 
material would be different, according to its capacity 
for heat. Thus quartz has a capacity nearly twice 
that of iron (sp. ht. 0.20) and water one of five times 
as much (sp. ht. i.oo). The temperatures would be 
reduced in proportion. 

If, instead of supposing the body homogeneous, we 
consider it heterogeneous, as indeed it is, and treat it by 
the simplest law consistent with physical principles and 
an approach to fact, to wit, that the density increases 
from surface to centre and that it resists compression 
in proportion as it stands compressed, — the formula 
assumed by Laplace, — we get an even greater amount 
of heat generated. 


We do not know the law of parting with this heat, 
though the greater portion of it was certainly radiated 
away in the process. But we may make some approx- 
imation, at least as between the several planets con- 
cerned, by assuming the heat near the surface to have 
been, at its maximum, what a body contracting from 
the density of its constituents, the meteorites, to its own 
eventual density would generate. We do this because 
the heat thus begotten proves in the case of the Earth 
to have been more than sufficient for all the volcanic 
and orogenic phenomena displayed. Now, as it is 
common physical knowledge that a small body cools 
quicker than a large one, we shall not err on the side of 
making Mars' internal heat too small if we apply the 
same principle to it. When we so evaluate the heat 
for the Earth and Moon,^ we get results as follows: — 
23,000° F. and 80° F. 

Here, then, we are landed in a quandary. If the 
Moon was generated on its own account, as the Earth 
and Mars were, the internal heat it was able to amass 
was never anything like the amount sufficient to pro- 
vide for the features which its surface shows. It could 
not even have kept itself from freezing amid the 
terrible cold of space. Now, it will be noticed that 
we said " if its genesis was like our own " ; that is, 
that it came into being by itself alone. In this saving 
"if" will be found the explanation of the dilemma. 


theory of 
lunar origin. 

Confirmed by 
lunar surface. 

Some years ago Sir George Darwin showed analyti- 
cally that the action of the tides in the Earth- Moon 
system, when traced backward, lands us at a time when 

From a photograph taken at the Lowell Observatory. 
A Part of the Moon's Face, showing Ancient Sea-boitom 

the Moon might have formed a part of the Earth's 
mass, the two rotating together as a single pear-shaped 
body in about five hours. His analysis pointed to 
what might have been. Now the pregnant point in 
our present heat inquiry is that the face of our satellite 
indicates that the might-have-been actually was. 

The erupted state of the Moon's surface speaks of 
such a genesis. For in that event the internal heat 


which the Moon carried away with it must have been 
that of the parent body — the amount the Earth-Moon 
had been able to amass. Thus the Moon was en- 
dowed from the start of its separate existence with an 
amount of heat the falling together of its own mass 
could never have generated. Thus its great craters 
and huge volcanic cones stand explained. It did not 
originate as a separate body, but had its birth in a rib 
of Earth. 

Far from disproving the law, the seeming lunar ex- 
ception, therefore, really upholds it. 

We may now go on to apply the principle to no Probable 
less interesting a determination — the case of Mars.^ comparative 

o internal neat 

If, taking into account the radiation which has cease- of earth and 
lessly gone on from the time when first the matter 
started to collect, we allow 10,000° F. for the effective 
internal heat of the Earth, we shall be making it a 
liberal allowance. Now, computation shows that an 
internal heat of 10,000° F. for the Earth would cor- 
respond to about 2000° F. for Mars. But the melt- 
ing-point of iron is 2200° F., so that iron would not 
have fused, and we should have in consequence virtu- 
ally no volcanic action. Furthermore, there could 
have been but little crinkling of the crust. For, first, 
the direct pressure was less, and then the heat, its indirect 
effect, was correspondingly small ; so that Mars can- 
not have contracted much, and so must largely have 



and oceanic 
areas formed. 

Their distri- 

escaped crumpling. What the contraction was may be 
inferred from comparison of its density with that of 
meteorites. The mean density of meteorites which 
are mostly stone with some iron is ^-S^ ^^^^ ^^ Mars 
4., and that of the Earth 5.5, water being unity. The 
planet should show, therefore, a remarkably smooth and 
level surface ; and this is precisely what the telescope 

The crust, to the folding of which a planet's physi- 
ognomy is due, was forming during all the time the 
planet took to cool on its surface from the temperature 
of the fusion-point of gneiss to the boiling-point of 
water, or from about 2000° F. down to 212° F. In 
some places it gathered thicker than in others ; and 
inasmuch as it floated, stood up higher, to which height 
crumpling contributed. Up to the time when its. 
liquefaction-point was reached, water existed only in the 
form of steam, but on the fall of the temperature to 
212° F. the steam fell with it, condensing into water. 
Into the troughs already there the water, as soon as it 
formed, proceeded to run. Thus the oceans came into- 

We may apply this to the Earth and consider an 
important consequent detail. The fashioning cause of 
the depressions that gave rise to the distribution of 
what we know as continents and seas is of great in- 
terest, for it seems to have been determined in a 



general way by cosmic considerations. If we scan a 
map of the globe, we shall mark a significant fact : 
that in all the continents a certain apexing to the south 
is discernible. Witness North and South America, 

View of Mars, showing the Proportion of Dark and Light Areas 

The dark areas are probably old sea-bottoms, and the light ones, desert land. 
Mars is here given of its true relative size as regards the Earth on page 21 — 
so that the actual surface of its former seas as well as their relative proportion 
to the land areas may be compared with those of the Earth. 

Greenland, Africa, and India. Blunt-based to the 
north, they all terminate in a tip southward. Australia 
is the only one of the great continental masses that 
fails to show the peculiarity at first glance. But a 


bathymetric chart reveals the fact that the platform on 
which it stands does indeed do so, Tasmania being 
really a part of it and making the detached tip. 
True Martian Nor docs the Earth alone present us with such 
message. curious Conformations, for Mars has a word to say on 

the subject. On casting one's eye over a map of that 
planet, one is struck by the triangular projections of 
the dark areas into the northern hemisphere. The 
Syrtis Major is the most conspicuous instance ; but 
the Margaritifer Sinus, the Sabaeus Sinus, and the 
Trivium Charontis exhibit a similar propensity. 
Now, when we reflect that the dark regions take the 
place of seas on Mars, this apexing of them to the 
north stands as the negative aspect of the positive 
picture presented by the Earth. Reverse the relative 
ratio of depressions to plateaux in order to get the 
seas and continents in their earthly proportions, with 
the oceans preponderant, as on Earth, instead of, as on 
Mars, in abeyance, and the two distributions are seen 
to typify the same action. 
Their relative The amount of surfacc the oceans covered on any 
Lent lanets P^-fticular pknct was again a consequence of the 
particular planet's size. If the material forming the 
planetary bodies was of the same general character 
throughout the fields they severally swept clear, which, 
to a certain extent, is probable, and the more so as 
the planets stand neighborly near, the amount of 



water each possessed would be as its mass, and when 
it collected into seas, these, if equally deep, would 
cover more of the surface in the larger planet, since it 

View of the Moon at the Full, showing the Proportion of Dark 
(so-called " Seas ") and Light Areas 

Only the darkest patches are thought to be sea-bottoms. 
Moon of true relative size to Earth (page 21) and Mars (page 29). 

has less cuticle for its contents. We have seen, how- 
ever, that this cuticle would be more crinkled and of 
greater accentuation in the larger body, owing to a 
greater contraction in the kernel within ; the folding 
we may perhaps take as being roughly proportionate 
to the radius of the globe. The larger body would. 


therefore, begin life with larger oceans, even if it were 
born with but its share of water ; but, as a fact, it 
would have more than its share because of being 
better able to hold on to its gaseous elements, and 
thus retain more of what was to condense to water 
when the time arrived. 

Now the three bodies, the Earth, Mars, and the 
Moon, have, or had, in all probability, judging from 
their present look, oceans in this order of size, the 
Earth having the most in amount. Mars the next, and 
the Moon the least. 

In the case of the Moon the matter is complicated 
by the fact that when it left the Earth it took probably 
not only a greater amount of light constituents than a 
solitary genesis would have permitted, but even a 
greater proportion than the Earth retained since it was 
born of the outer and therefore lighter layers of 
the Earth-Moon mass. It thus started more pro- 
fusely endowed with the wherewithal to oceans than 
its size warranted. 
Earth's On all three planets their primeval topography has 

oceanic asms pj-Q^g^ persistcnt. On both the Moon and Mars the 

unchanged. ^ ^ 

dark areas are apparently the lowest portions of the 
surface, while their character points to their having 
held seas once upon a time. With Mars it is 
their present occupancy, though by something other 
than water, that tells the tale ; with the Moon the fact 


that rays and rills run athwart them discloses it, be- 
speaking their age. 

Turning to the Earth, according to the best evidence 
we possess, the great ocean basins have remained un- 
changed in place from the period when they were laid 
down. Not that the areas marked out as land and 
water at any epoch have not greatly altered since the 
beginning of geologic time; but the abyssal depths on 
the one hand, and the continental platforms on the 
other, have not substantially varied during all these 
ages. If we examine a bathymetric chart of our 
several oceans, giving their body by registering their 
depth, instead of a superficial one which marks simply 
where the water laps the land, and consider the one 
hundred-fathom line, the ocean bottoms and the con- 
tinental plateaux stand, well differentiated from each 
other. It is then seen that each continent is set on a 
shelf wider in some places than in others, but at its 
edge falling abruptly to the marine abysses, which, 
though themselves uneven, stand, with the exception 
of a few islands, projecting and submarine, at a gener- 
ally much lower level. This indicates that they have 
always held such attitude. 

But the character of these ocean bottoms furnishes Their floor- 
the best testimony that they have not changed during '"^ ^"^'^' '^' 
geologic time. Their flooring is organic ooze or inor- 
ganic clay, globigerina, radiolarian, or diatom ooze, 


according to locality and depth, and red clay formed of 
the decomposition of volcanic stuff. In this ooze and 
clay, spherules of metallic iron, identified as similar in 
substance to that of falling stars, are still recognizable 
in perceptible amount, and as they must accumulate 
with exceeding slowness, their patent presence asserts 
the absence there of sedimentary silt from any shore. 
These abysses, then, have always been abysses from 
the start. That astronomy should tell us this is 
strikingly suggestive, while of peculiar planetologic in- 
terest is it that meteors again should be our inform- 
ants of the fact. 



UPON the fall of the temperature to the condensing The origin 
point of water, occurred another event in the u^-g 
evolution of our planet, the Earth, and one of great 
import to us : life arose. For with the formation of 
water, protoplasm (the physical basis of all plants and 
animals) first became possible, what may be called the 

Model of a Brontosaurus, a first Possessor of the Earth's Land, in 
THE American Museum of Natural History* 

The fossil skeleton is 15 ft. and 2 in. high and 66 ft. and 8 in. long. 

life molecule then coming into existence. By it, 
starting in a simple, lowly way, and growing in 
complexity with time, all vegetable and animal forms 

* This illustration and those succeeding it to page 41 were kindly furnished the 
author for the purpose, by Professor Osborn. 



have since been gradually built up. In itself the 
organic molecule is only a more intricate chemical 
combination of the same elements of which the inor- 
ganic substances 
which preceded it 
are composed. It 
j?A '?'W^ \ is. thus carrying on 

the building-up 
process begun by 
the inorganic be- 
fore it. Between 
the organic and 
the inorganic, in- 
creasing knowl- 
edge, by pushing 
back to greater 
and greater sim- 
phcity the forms 
of life discovered, 
has tended to 
break down the 
barrier man had 
assumed to exist. 
There is now no 

Plant Life in the Coal Measures ^°^^ reason tO 

From a fossil specimen in the American Museum of QOUDt that plants 
Natural History, found in Illinois, here shown /- , 

two-thirds its size. gfew out of chcm- 


ical affinity than to doubt that stones did. Spon- 
taneous generation is as certain as spontaneous varia- 
tion, of which it is, in fact, only an expression. 

But it is not spontaneous generation in the popular 
sense. By that term many persons think of flies 
suddenly born of decaying meat, and this they know 
has been shown impossible. But this is simply be- 
cause flies are far too advanced a product to be thus 
suddenly evolved. For them to be so produced 
would as directly controvert all we know of evolution 
as that, given the proper conditions, the lowest rudi- 
ments of life would not arise. That even the latter 
may nowhere be evolved on earth at the present time 
does not invalidate such origin for it when the con- 
ditions were other than they are to-day. 

From all we have learned of its constitution on the Life an in- 
one hand, or of its distribution on the other, we know ^^f\ ^ ^ ^^^ 

^ ^ of planetary 

life to be as inevitable a phase of planetary evolution evolution. 
as is quartz or feldspar or nitrogenous soil. Each 
and all of them are only manifestations of chemical 
affinity resultant on condition, and considering the 
oneness of the stuff, it is the conditions alone we 
have to investigate if we would learn what is to come. 
Virtually only six so-called elemients go to make up 
the molecule of life. It is the number of its constituent 
atoms, and the intricacy of their binding together, that 
give it the instability to produce the vital actions. 



Carbon, hydrogen, oxygen, nitrogen, phosphorus, and 
sulphur are practically all that are required. If a 
planet be capable of furnishing these under suitable 

temperature con- 
ditions, it seems 
as inevitable that 
life will ensue as 
that the two ele- 
ments sodium and 
chlorine will unite 
to form common 
salt when the heat 
and the pressure 
are right. Now, 
on its face, it is 
suggestive of the 
u niversality of life 
that the elements 
that go to form it 
are of all elements 
the most wide- 
spread. Oxygen, 
the chief factor 
in all organisms, 
makes by weight 
one-half the substance of the earth's surface ; 
silicon, a large constituent of shells, comes next in 

Plant Life of the Upper Devonian 

From a fossil specimen in the American Museum 
of Natural History, found in New Brunswick. 


amount ; and the others follow In the constitution of 
life about in the order of their natural abundance. 
For proof of the continuity of the processes of both 
structure and change in the inorganic and organic alike, 
nothing at once more conclusive and more interesting 
can be recommended than the books of the great 
Haeckel, couched in language every educated person 
can understand. 

Of all the conditions preparatory to life, the presence Water 
of water, composed of oxygen and hydrogen, is at once ^^^J" ' 
the most essential and the most world-wide. For if 
water be present, the presence of other necessary ele- 
ments is probably assured because of its relative light- 
ness as a gas. Furthermore, if water exist, that fact 
goes bail for the necessary temperature, the gamut of 
life being coextensive with the existence of water as 
such. It is so consequentially, life being impossible 
without water. Whatever the planet, this is of neces- 
sity true. But the absolute degrees of temperature 
within which life can exist vary according to the mass 
of the body, another of the ways in which mere size 
tells. On the earth 212° F. (100° C.) limits the range 
at the top, and 32° F. (0° C.) at the bottom in the case of 
fresh water, 27° F. (— 3° C.) in the case of salt. On a 
smaller planet both limits would be lowered, the top 
one the most. On Mars the boiling-point would prob- 
ably be about i io°,Fo (43° C.).^ Secondly, from the 


general initial oneness of their constituents, a planet that 
still possesses water will probably retain the other sub- 
stances that are essential to life : gases, for the reason 

A Trilobite, one of the Earliest Forms of Animal Life preserved 

From the fossil specimen in Niagara shale, in the American Museum of Natural 
History, here shown two-fifths natural size. 

that water-vapor Is next to hydrogen, and helium the 
lightest of them all ; and solids because their weight 
would still more conduce to keep them there. Water, 
indeed, acts as solution to the whole problem. 

Water plays a protagonist part In the origination 
and the development of protoplasm by constituting 



at least nine-tenths of its substance. But, to begin 
with, it actually furnished the stage-setting for the 
drama of life by providing a medium in which it 
could evolve and 
function. This all- 
important use of / 
water by living 
organisms is shown 
both by the pres- 
ent state of all ani- 
mals and plants and 
by what science is | 
discovering of their 1 
past history. I 
There never was I 
a time, and there ] 
apparently never 
will be a time, when 

plasm can do with- f ■ /^ 

out that indispen- 
sable ingredient of 
life. At first, in 
the lowest unicellu- 
lar plants and animals, it forms the whole environment, 
completely enveloping the organism. Thus the simplest 
cells are found in the sea, in ponds, and even in hot- 
spring geysers nearly at the boiling-point. In fact. 

Fossil Footprints of Amphibia 

From a slab reproduced in Professor Edward 
Hitchcock's " Report on the Sandstone of the 
Connecticut Valley." 


Seas the 
earliest home 
of mundane 

far from this last habitat being peculiar, it is in such 
warm baths that plasm undoubtedly took its rise. 
Protophyte and protozoa lived in a sea that to us 
would have been fatally hot. 

Here is the reason for the contemporaneous ap- 
pearance of oceans and of life : the one was the neces- 
sary home of the other. That it was so in fact 
geology states. The geologic record proves that*life 
originated in the oceans, and lived there for long eons 
before it so much as crawled out upon the land. Seas 
were the nurseries of mundane life. Whether life 

might have gen- 
erated on land 
we do not know ; 
on earth it cer- 
tainly did not, 
possibly because 
seas were intrin- 
sically the better 
habitat in place 
and in time for 
the uniformity 
of the conditions 
they offered ; possibly because they were all the home 
there was. For the land was a sorry spectacle in those 
days. Granite fringed by mud-flats pictures but an in- 
hospitable sight. The seas were much as they are now. 

Specimens of Deep-sea Fish 

These specimens were obtained by the Challenger Expe- 
dition from a depth of about 500 fathoms (3000 feet). 
They illustrate Ufa formerly thought impossible. 


only warmer. Their equable temperature for wide locali- 
ties and their slow accommodation to climatic change 
rendered them places of easy livelihood to simple organ- 
isms. In addition to which, food, inorganic at first, was 
floated past the baby plants or animals, and as con- 
stantly renewed. To its seas and oceans our planet, 
then, is actually, if not necessarily, indebted for the 
life which now teems everywhere upon its surface. 

Life, once started, continued the course of advance- 
ment thus aquatically begun just as itself was the 
continuance of the inorganic development which had 
gone before. And the deus ex machina was the same 

— a gradual lowering of temperature. Cooling was 
what occasioned increasingly high forms of life, and in 
two ways this was simultaneously brought about — by 
preparation of habitat and by prompting of the organ- 
ism to appropriate it. 

The record written in the rocks of our own earth 
permits us to trace the history of the spread of life. 
With the gathering of the waters into their place 
began a new stage in the world's physiographic career 

— the stage of sedimentary formations. Until the 
seas were, no strata could be laid down ; but with 
their advent both motive force and suitable sites were 
present, and, in consequence, what the welkin-born 
torrents tore down of the naked earth was deposited 
over the edges of the continents, now here, now there. 


according as upheaval or subsidence slightly changed 
the continental altitude toward the sea-level. One 
bed after another was thus made, until they were sev- 
eral thousand feet thick in places, each being tucked into 
its long repose by later coverlets superposed upon it* 
Entombed in these strata are the skeletons of all 
those animals that a not too flimsy structure permitted 
to survive the casualties of flood and commotion or 
the long disintegration of time. The softer ones have 
necessarily vanished, leaving as a rule no trace. The 
rocks are thus vast graveyards of life that once inhab- 
ited the earth. They give us the only direct record 
of the past, and a record which from the necessities of 
the case is perforce imperfect. Especially are the 
earlier chapters effaced for the gelatinous character of 
primeval protoplasm and the forms it first built up. 
Thus the earliest preserved remains of life are already 
somewhat advanced types, Crustacea in the shape of 
trilobites being the most primordial specimens that 
have come down to us in unquestionable state. From 
this lowly start the line can be followed upward, un- 
folding through the strata, the marvellous thing being 
not the paucity, but the fulness, of the record thus 
written by the animals themselves. For animals and 
plants, too perishable to endure, have left their stamp 
behind, and even footprints of past reptiles confront 
us, legible still on the hardened sands of time, as if 


made yesterday in the spots they traversed hundreds 
of centuries ago. 

According to their age, the rocks are designated by Uniformity 

1 • • 1 ^ . ^ . of paleozoic 

geologists as primary, secondary, or tertiary formations, ^^J^, 
representing paleozoic, mesozoic, and c?enozoic eras, 
meaning the old, the middle, and the new hfetimes, so 
called from the remains embedded in them. 

For our purpose, the most remarkable characteristic 
of the primary rocks consists in the world-wide uni- 
formity of their contemporary life as exhibited in these 
fossils of the far past. In the earliest beds existent 
species prove to have been coevally widespread. In 
the Cambrian, the lowest of the primary strata exhibit- 
ing unmistakable organic remains, we find identical 
species of seaweeds and trilobites appearing, regardless 
of latitude, in France and Siberia; and indifferently on 
both sides of the equator, in the Argentine Republic, 
as in Europe and North America. In the beds above 
these, the Silurian, it is the same story. Some of the 
genera and even some identical species have been 
found alike in Europe and North America and in Tas- 
mania, Australia, and New Zealand. Evidence of a 
like latitudinarianism is forthcoming in the Devonian 
deposits that followed them and in the early stages of 
the succeeding Carboniferous. 

The fauna so distributed was a warmth-loving one, 
an attribute betrayed by the fact that their nearest 


relatives now extant live wholly within the tropics, 
huddled as it were about the equator. Coral reefs, 
now not found outside of the warm equatorial seas in 
a temperature not less than 68° F., were reared then in 
spots now covered with perpetual ice, within eight 
degrees of the pole. A species of polyp coral, Litho- 
strontion by name, has been found as a fossil between 
Point Barrow and Kotzebue Sound, and others in 
Grinnell Land in latitude 8i° 45' north. 

At first the fauna was wholly marine, but gradually 
the land grew less impossible. Wings of insects have 
been found in the Lower Silurian, and in the Upper, 
insects themselves, scorpions both aquatic, apparently, 
and terrene. Vestiges of plants in the Devonian fore- 
shadowed the superb plant life of the Carboniferous. 
Carboniferous The flora of the coal measures corroborates the tes- 
timony of the animals of that day to the climatic 
warmth which then existed. Gigantic ferns, fifty feet 
high ; others, more lowly, thirty feet in spread ; marsh- 
loving calamites, horsetails, and club-mosses, dignified 
to the dimensions of trees, spread their incipient leaves 
from well-nigh woodless stems, and grew, flourished, 
and decayed with almost Jack-and-the-beanstalk rapid- 
ity between 23° ^^^ 70° of latitude. Only a warm, 
humid foothold and lambent air could have given them 
such luxuriance and impressed them with such speed. 
In the vast marshes which constituted so large a 

plant life. 


portion of the continents this vegetation was singularly 
same. Not pretty, but profuse ; dense, but not varied, 
cryptogams composed its greater part, attesting by the 
habit of the ferns of to-day to the shady half-light in 
which they must have lived. Grotesque rather than 
beautiful, no flowers touched with color the sombre 
stems. No birds made the air about them half sentient 
with song. Only shade-affecting insects, May-flies of 
mammoth wing, flitted through the gloom of those old 
forests, accentuating a heavy stillness they were power- 
less to dispel. 

The twilight their character thus reveals is shown 
by the details of their structure to have been continu- 
ous. No seasons diversified the work of wood-making, 
as the uniform stems of the few gymnosperms then 
present attest. No annual rings of growth encircle 
them, witnessing to intermediate times of rest. They 
minded not extraneous things, but grew right on ; not 
to dehght the world, but to make coal measures their 
industrious end, to which in their own blind way they 
excellently conformed. Blind in their habit they may 
be said to have been, for they were flowerless and 
much restricted of leaf. 

Two attributes of the climate this state of things 
attests. First, it was warm everywhere with a warmth 
probably surpassing that of the tropics of to-day ; and, 
second, the light was tempered to a half-light known 




now only under heavy clouds. And both these con- 
ditions were virtually general in locality and continuous 
in time. For such vegetation as existed the climate 
was ideal. No enforced hiemal torpor brought on by 
stalking delegates of frost compelled the workers con- 
stantly to stop. It is their less fortunate descendants 
only that are limited by nature's imposings to labor 
but six months a year. 
Light less and Thus the rccords of the paleozoic rocks bespeak two 
more seemingly incongruous things — both less light and 
more heat than is the Earth's lot nowadays. Many 
hypotheses have been invoked to account for this 
warm dawn of the early geologic ages. Some of them 
are locally geologic, some broadly astronomic, advanced 
by geologists. But of the two kinds all alike fail. 

Thus, merely a different distribution of land and 
sea will not explain it, because it was general, not local; 
and, secondly, because this leaves untouched the prob- 
lem of less light. Equally impotent is a change of 
position in the axis of the Earth ; for were the axis so 
far changed as to point directly toward the sun, this 
would not do away with the seasons, but would accen- 
tuate them. Nor will an altered eccentricity in the 
Earth's orbit, which has also been suggested, prove 
more effective. 

Not less impossible is the suggestion due to M. 
Blondet, and to which De Lapparent has lent the 


weighty Indorsement of his name, that the sun was 
then so large as to be able to look down on both poles 
of the Earth at once, and so to give our globe equal 
day and night everywhere and, as he supposes, a sub- 
stantially even temperature in consequence throughout. 
Here the beauty of that to many people deterrently 
austere and awe-enshrouded subject, mathematics, 
comes in. For it enables us to do that most impor- 
tant thing for any line of investigation — to subject it 
not simply to qualitative, but to quantitative, reasoning. 
When we thus calculate what this paleozoic sun must 
have been and what its effects, we are brought up on 
both counts against impossibilities. 

The first impossibility relates to the sun itself. For 
it to do as desired it must have filled all the space 
inside the orbit of Mercury. For a sun of such stu-. 
pendous size there is no place in modern cosmogonies. 
On the other hand, it would have been of incredible 
tenuity, only one-fifth as dense as hydrogen gas. 
Nor is this all. It must have been thus uncondensed 
at a time when the Earth had already solidified. The 
conception evolutionarily is quite incredible.^ 

Matters are not bettered for the theory if, passing Effect on the 
by the results consequent on the Sun, we calculate 
those ensuing to the Earth. 

We perceive, in the first place, that the exposure to 
the Sun*s rays in the arctic regions would have been 


by no means unifornij but would have varied greatly 
with the time of year. At latitude 82° N., for instance, 
the exposure would have been virtually nothing at 
midwinter; 25 per cent of what it would be now at 
the equator, at the vernal equinox, and 1.24 per cent 
of that, at the summer solstice. So that the play of 
the seasons would have been much as now. 

Secondly, we find that at the arctic circle the solar 
heat in midwinter would equal that at present in lati- 
tude 60° N., and even at the equinox 82° N. in those 
times would be no more heated than is now 46° N. in 
midwinter. A Quebec winter six months long does 
not quite supply an adequate temperature for the 
bringing up of a polyp coral family within ten degrees 
of the pole.^ 

So that, when subjected to mathematical treatment, 
the supposed paleozoic sun turns out to -be quite im- 
potent to the work demanded of it. The theory fails 
as regards the Earth as much as it does with reference 
to the Sun. 
Earth itself Planctology, howcvcr, can offer us a clew to this be- 

responsi e or ^Jq^j^^ hothousc statc of things. Thc Earth's own 

paleozoic heat. o 

heat, not directly on the crust, but directly on the 
water, and thence through its atmosphere, might well 
be responsible for paleozoic conditions. For consider 
the warmth we know must have existed while the re- 
cently precipitated seas still were hot. Their temper- 


ature would furnish an agreeably heated habitat for 
organisms such as even the tropics fail to supply to- 
day, and one which from its genesis would be much the 
same from the equator to the poles. Simultaneously, 
a vast steaming must have gone up from the still 
warm waters, resulting in a welkin of great density. 
This would act in two ways to explain the phenomena. 
First, the welkin would keep the Earth's own heat 
in; and, secondly, it would keep the Sun's heat and 
light out. We should have a sort of perpetual trop- 
ical summer in a twilight of cloud; a climate superior 
to seasons because screened from direct dependence 
on the elevation of the sun. This is perfectly in ac- 
cord with the half-light the vegetation vouches for, 
while the luxuriance of that vegetation testifies to the 
warmth and even suggests a further, though not the 
chief, reason for it in the great amount of carbonic 
dioxide its existence establishes as then present in the 
air.^^ For carbonic dioxide is a great bar to the pas- 
sage of heat. So is water-vapor. It was dank and 
dark in those old carbonic forests because so seeth- 
ingly steamy overhead. 

That the oceans should have retained their heat so 
long is not surprising when we reflect upon the great 
capacity that water has for heat. Its specific heat, 
which means the relative amount needed to raise it one 
degree in temperature, is five times that of stone, and 



Earth, not 
sun, the 
motive force 
in evolution 
in the pale- 
ozoic era. 

ten times that of iron. So that it would have more to 
part with than its surroundings, and would still be 
warm and steamy after they had cooled. 

In paleozoic times, then, it was the Earth itself, not 
the sun, to which plant and animal primarily stood 
beholden for existence. This gives us a most instruc- 
tive glimpse into one planetologic process. To the 
planet's own internal heat is due the chief fostering of 
the beginnings of life upon its surface. Thus a planet 
is capable of at least beginning to develop organisms 
without more than a modicum of help from the central 
sun. We talk of the sun as the source of life ; and so 
it is to-day in the sense of being its sustainer ; but the 
real source was the Earth itself, which also raised it 
through its babyhood. 

Something of the same history probably fell to the 
couay ars. ^^^ ^^ Mars. Scvcral circumstances render this likely. 
If its initial surface temperature was in the neighbor- 
hood of 2000° F., it was well above the production- 
point of steam. So that a cloud canopy would be 
possible when a general volcanic fervor of the surface 
was not. Then the apparent presence in those early 
days of seas would furnish the wherewithal of clouds. 
Thus Mars would seem to have possessed the neces- 
sary substance to its veiling, and the requisite con- 
ditions to that end. If a planet be big enough to 
bring forth life, it may well provide a set of atmos- 

A once 


pheric swaddling-clothes in which that hfe goes through 
its early days. 

Under such paleozoic conditions Hfe passed the first Life outgrows 
eons of its earthly existence. Gradually hfe outgrew 
the need of such careful housing, water within the 
organism remaining as necessary as before. Organic 
development proceeded from amoeba to fish, attaining 
no mean height in the process. But at last a better 
habitat offered itself, and was speedily appropriated. 
Weathering of the land and constantly changing 
chemic processes prepared the continents for organic 
use. Plants, as we have seen, at last found foothold, 
and insects an abode. Then came the exodus from 
the sea. We may picture some adventurous fish, 
spurred blindly from within, essaying the shore in 
preference to the main. Tentatively at first he must 
have ventured, as became such bold endeavor. Find- 
ing the littoral not inhospitable, the pioneer reported 
his exploit and was followed by others whom mutation 
had specially endowed. This impulse toward the new, 
from the promptings of altered character, which we call 
spontaneous variation, is the motive principle of life. 
It probably derives from the instability of the plasmic 
molecule, forever rearranging its constitution afresh 
and finding itself thus adapted to novel relations. 
Thus arose the amphibia in the Carboniferous era, vis- 
itors only to the solid ground. From them came the 


reptiles, their descendants, in the Permian, who, from 
the temporary sojourners their fathers were, devel- 
oped into permanent denizens of the new abode. 
From this aboriginal crawling out upon terra firma 
the organism progressed until finally it came to stand 
erect and call itself a man. 

Changed habitat made all the later strides in intelli- 
gence possible. The very sameness that rendered the 
sea so inviting a habitat to simple souls, made evolu- 
tion beyond a certain point difficult, if not impossible. 
Change might develop in the organism, but it would 
find little encouragement to survive in its surround- 
Effect of It was the variety of conditions possible on land 

environment ■, • . • , i i • • 

, that gave rise to varvmg environment, and this in turn 

upon evolu- o / o -' 

tion. that conduced to organic differentiation. Life would 

have remained forever of a low, cold-blooded order if 
it had been constrained to continue in the sea. What 
made the broad ocean so excellent a nursery curtailed 
it as a field for action later on. 

To appreciate how unsuited to high development 
of organism the sea was, we need only think how poor 
a place it is for bringing up a family. Fishes cast 
their spawn upon the waters, and leave the hatching 
of the eggs to chance. If one in a million survives 
this unparental treatment, it is all that nature expects. 
The fish has done well, and its tribe increase. This is 


taking but little thought for the morrow. The poor 
little egg is homeless as well as parentless from the 
start, lacking even that attenuated appreciation of home 
surroundings Gallicly expressed as mal du pays, since 
one tract of ocean so dishearteningly resembles another. 

Very different is the care of their young exhibited 
by the higher land inhabitants, the mammalia. With 
them the mother begins by carrying the egg in the 
safest possible way, as a part of herself, until it has 
become to all intents and purposes an. animal on its 
own account. It then sees the light, but not the limit 
of fostering care. She keeps it by her, suckling it till 
it is able to procure food for itself. Even then its 
guardianship is not in the highest forms foregone. In 
man parental help continues up to the point when the 
young is full grown, and even after that, on through 
life, till the next generation has become the dominant 
one of its day. 

To say the least, life was an arduous, adventurous 
career amid the inhospitable homelessness of the sea. 
And this is shown not only by the leaving it at the 
first opportunity by those who could, but by only 
degenerates returning to it again. Only the poor 
relatives of the mammalia — the porpoises, dugongs, 
and whales — -are now to be found there, having taken 
to it through stress of circumstances, elbowed off the 
better ground by their stronger associates. 


That the outcasts still exist, however, proves the 
tenacity and adaptability of life. It goes everywhere, 
takes up with what it can get, and turns the least pro- 
pitious milieu to its own ends. For life is more univer- 
sal than is our usual conception of it. Our limited 
personal experience we take as measure of the whole,, 
and say, " Thus far and no farther." But nature 
knows no such limit to her own possibilities. And 
we are gradually, one may almost say reluctantly,, 
learning them of her. Go where he will upon the 
earth, man finds life of some sort there before him. 
He discovers new continents or seas merely to find 
out that they had been discovered by some poor rela- 
tives long ago, and appropriated by them. From 
burning Saharas to polar snows no spot is exempt 
from colonization, though some teem with immigrants 
more than others. In altitude it is the same story as. 
in latitude. If man ascends, he meets with forms of 
life that rise with greater facility than he, and inhabit,, 
too, what they explore. In descent it was until re- 
cently thought otherwise. One region was supposed 
free of such intrusion and to have remained as virginly 
azoic as when originally formed — the unstirred abysses 
of the vast oceanic basins, all that constitutes the great 
deep beyond the immediate vicinity of the shore and 
below the hundred-fathom line. No hfe existed, man 
was sure, in the depths of the sea. 


Fifty years ago the absence of both flora and fauna Deep-sea life 
from the deep seas was not only taken for granted, but ^ ""^ ^ *"™" 
beheved on the most conclusive grounds to have been years ago. 
proved inevitable. The first of these was the enor- 
mous pressure to which any organisms resident there 
would be subjected. From the weight of the super- 
incumbent water the pressure would increase at the 
rate of one ton per square inch for every thousand 
fathoms of descent. 

Consequently, at the bottom of the Atlantic, it would 
be from two and a half tons to three and three-quarters 
tons per square inch, and in the greater depths of the 
Pacific from three and one-half to nearly ^vg tons. 
On bodies at the earth's surface, living only under the 
ocean of air, it is but fifteen pounds to the square inch. 
FVom fifteen pounds to ten thousand is a far cry, and 
one it staggers imagination to understand. It was 
only too easily argued as prohibitive to life. Any 
organism there, it was thought, would simply be 
crushed out of existence. 

The second bar was the total extinction of light. Extinction 
Below two hundred fathoms no sunlight could pos- ° '^ ^' 
sibly penetrate. So it was calculated from the rate 
at which light is absorbed at lesser depths, and the 
calculation was amply borne out by observation. 
Experiments by Fal and Sarasin have fully demon- 
strated the unassailability of this deduction. On a 


sunny day in March they exposed bromo-gelatin 
plates for ten minutes at a depth of two hundred 
fathoms without a trace of reaction. To those who 
know by experience how quickly plates fog in a dark- 
room, this immunity speaks for the more than Stygian 
darkness which must there prevail. 

Now, the lack of light is distressing enough to any 
fauna, but to flora it is absolutely preclusive, since 
light is the necessary stimulus to chlorophyl reaction, 
and thus to the growth of the plant. But if all plants 
be absent, animals, it was confidently concluded, must 
be absent, too, since they could not live without plants, 
being unable to fashion their food out of inorganic 
substances. They must eat plants or other animals 
that have eaten plants. Therefore, after the stronger 
inhabitants of these abyssal depths, supposing any 
there, had eaten the weaker, they must themselves die 
of starvation. 

These arguments seemed unanswerable, to say noth- 
ing of the abyssal cold. For the temperature falls as 
the thermometer descends until at a depth of a few 
hundred fathoms in the unbarriered ocean basins it 
reaches a temperature of 34° F., whence a slow falling 
further brings it to 29° F., or actually below the freez- 
ing-point of fresh water. 
Deep-sea life. When it had thus been conclusively proved that 
no life could exist at the bottom of the sea, deep- 



Specimen of a Deep-sea Fish 

This specimen was obtained by the Challenger Expedi- 
tion from a depth of about 500 fathoms (3000 ft.) and 
illustrates life formerly thought impossible. 

sea dredges were inventedj and no sooner were they 
let down than, behold ! they came up teeming with 
life. Fish and 
Crustacea, mol- 
lusks and echi- 
noderms — life, 
in short, of all 
the usual pelagic 
kinds from pro- 
toplasmic mole- 
cules to marine monsters — were found to inhabit the 
abysmal depths. What could not be, just was. 

The abyssal fauna thus disclosed proved to be in 
comfortable circumstances, in spite of the supposed 
impossibility of its existence at all. It had, it is true, 
no visible means of subsistence, but it subsisted, never- 
theless. It was as widespread as it was abundant, en- 
joying a distribution unknown on land. The same 
species were found off the coast of Europe and about 
New Zealand, in the arctic seas as well as under the 
tropics. This was because of the uniformity of the 
habitat. Only seven degrees of difference in temper- 
ature distinguished one part of its huge domain from 
another. There was therefore no bar to migration ; 
indeed, the sameness of the surroundings must have 
insidiously led the inhabitants on. A species was thus 
induced to become world-wide, while on land, even 


supposing a pathway to exist, the journey from one 
hemisphere to the other involved enduring a shift of 
ioo° F. or 150° F. of temperature, made as it would 
be from winter in the one to summer in the other. 
No such temporalities as seasons disturb the abyssal 
pelagic denizens, nor can locality have meaning to 
them, even though they be associated with the bot- 
tom, which is only ooze or mud — ooze, the burial- 
ground of protozoa, and mud, the siftings of volcanic 
lava mixed with meteoric dust. One place is like 
another, bearing no earmark, and a fish returning to 
the very spot of its nativity would not know it again. 
Time and space are alike annihilated there, and both to 
sense made limitless. If any creatures can feel infinity, 
it must be these abyssal denizens of the deep sea. 
Blindness. The supposcd impossibilities of their abode Nature 

has contrived to surmount. The pressure permeates 
them, and their parts are constructed to stand the 
strain. Yet so little change has been needed to adapt 
them that it is virtually imperceptible to the cursory 
eye. In another way Nature has accommodated them 
to the illumination of their habitat. She has let them 
get on without seeing or she has provided them with 
lamps. By supplying senses other than the eye, and 
allowing the animals to become bhnd, Crustacea and 
fishes alike, she has made them independent of the 
darkness. Or she has done for them what man has 


accomplished for himself — supplied artificial illumina- 
tion. That a blind fauna should exist in a vast do- 
main with not so much as a one-eyed specimen for 
king, is interesting and suggestive of what Nature can 
contrive to do without, but that she should undertake 
to light the region, and that by means of the creatures 
themselves, is yet more surprising. 

But this is precisely what she does, and with some- Phospho- 

, . , . ... , . , . • 1 • rescent organs. 

thmg akm to electricity, each animal carrying with it 
its own machine. Whole tracts are brilliantly lighted 
up by the inhabitants till they must resemble London 
or Paris seen by night, only that in these thoroughfares 
of the abysses of the sea the passers-by provide the 
illumination, each, as it swims about, swinging its own 
lantern as in old Japan, though better — a phospho- 
rescent arc-light, as one may say. These devices are 
evident even when the fish, no longer living, reaches 
the surface in the dredge ; much more brilliant they 
must be in their native wastes of abysmal water, where 
all is cold and dark and silent round about, as impres- 
sive as a mountain top at midnight, standing con- 
fronted with the stars. 

How thoroughly the living by artificial light is now Lesson of the 

r ^ • 1 • 1 • r fishing fishes. 

a part or their everyday existence, the occupation or 
angling practised as a means of livelihood by certain 
of the fish themselves — fish that fish and are known 
in consequence as angler-fish — will serve to show. 


Specimen of a Deep-sea Fish 

This globular specimen is an angler-fish, which has 
kept to the habit of angling, but has changed its bait. 
From the Challenger Expedition. 

On the surface the genus given to this profession are 
furnished with a long tentacle which, rising from the 

back, curves over 
by its weight till 
the end, which is 
lobed into a red 
bunch not un- 
suggestive of a 
tempting worm, 
dangles right in 
front of the 
fisher's mouth. 
Smaller fry, attracted by this bright bait, dart forward 
to gulp it, and are themselves snapped up by the 
expectant jaws. 

Now, of these angler-fish one species proves to in- 
habit the abyssal zone ; and this relative of the anglers 
above, instead of the red worm-like bait at the end of 
its rod, which would be useless in the Stygian darkness 
thereabout, has replaced it by a brilliant, phosphores- 
cent light, which lures as certainly to destruction. 
Adaptation could offer no more expressive example 
of the insistence of life, even to the preservation of 
the very type, than this keeping of the fishing habit 
with only a change of bait. 

After such an ingenious transformation, the substitu- 
tion of lungs for gills when the aquatic animal changed 


into the terrestrial one, seems a forthright step in 
comparison. The swim-bladder, discarded when the 
descendants of the upper relatives of these animals 
emerged, leads to some curious experiences at the 
bottom of the sea — ones that induce new outlooks 
on life, and yet are the result of conditions alone. To 
us who live upon the solid crust, pulled downward 
constantly by gravity, danger lies in faUing over preci- 
pices or down holes. Abyssal fish are exposed to no 
less a risk, but of precisely the opposite character — 
that of tumbling upward. Within limits, the fish 
has control of his 
swim-bladder, but 
if in the excite- 

ment of the chase Specimen of a Deep-sea Fish 

he P;etS carried bv Obtained by the Challenger Expedition, 

impetuosity farther up than he intended, he may reach 
regions where, for the lessened pressure, he can no 
longer control its distention, and is swept against his 
will higher and higher till his organs burst from the 
released strain. The fish tumbles upward, and is 
killed by the fall. 

As for the flora, it simply does not exist. Never- 
theless, the absence of a local food supply is not fatal 
to these denizens of the deep. It would seem that 
what descends to them from the waters above is 
enough, meagre as it may be. They feed off the 


crumbs that fall from the better-spread table of their 
littoral relatives, as is shown by their being the 
descendants of emigrants thence. For most of them 
have relatives still living in shallow water, the oldest 
abysmal species not dating farther back than Cretaceous 
Cosmic char- From such world-widc distribution of life over the 
Earth under conditions which are antagonistically 
unlike, we realize its essentially cosmic character 
experimentally, if we may so put it, as well as 
theoretically. Modifications of it follow any and 
every change of environment, but nature strives to 
the last gasp to bring forth this, her highest 

Each planet sets a different stage for the play of 
spontaneous variation. In no two is the scenery the 
same, but this is not essential to organic origin and 
growth. Nor are many of the environmental circum- 
stances prohibitive, though at first they seem fatal to 
our particular species of life. Because a man, if sud- 
denly transported to Mars, would gasp and die, is as 
beside the point in any inquiry into the existence 
of life there as the fact that no woman ever was the 
mother of a monkey is irrelevant to a discussion on 
the origin of man. We have here been evolving in 
keeping with the shapings of a certain environment. 
To suppose that we could instantly prove adapted 


to another quite diverse is to mistake the process 
upon which hfe depends. 

Indeed, our most commonplace actions would there 
seem phantasmagoric. Personal experience of Mars, 
on the surface of which gravity is only three-eighths 
the Earth's, would take on a character akin to the 
grotesque. Everything there would become unnatu- 
rally light : lead would weigh no more than stone with 
us, stone than water, each substance appearing to be 
transmuted into something other than itself It would 
prove at once a world imponderable, etherealized. 
Our actions would grow grandific. For with little 
effort we should accomplish the apparently impossible, 
endowed with an effectiveness increased sevenfold. 
Lastly, everything would take its time. Water would 
flow with hesitant and lazy current, and falling bodies 
sink with graceful moderation to the ground. After 
our first paranceac wonder, it would certainly impress 
us as a world as slow as it was flat. 

Our very senses would seem estranged. Sight, 
indeed, and taste would be the only ones not to be 
shifted in their point of view. Touch, hearing, even 
smell, would all suffer a space-change and prove quite 
other than we know them now. We should be any- 
thing but at home. But this does not imply that life 
of some form would not. For consider how our 
own world must seem other than we know it to every 


animal upon its face. To the ant it stands a very 
different habitat from what the elephant conceives it. 
The grass-spires which tower as trees to the one are 
trodden unnoticed ui:derfoot by the other. Nor is it 
matter of mere magnification alone. The former feels 
both strength and limitations the latter quite ignores. 
The ant scales his grass-stem with an ease and assur- 
ance we should not know on trees, and falls off to the 
ground, if need be, completely unscathed from a rela- 
tive height that would terminate our careers forthwith. 

But though modified in feehng by size of habitant 
and modified in fact by size of habitat, life would go 
on superior to such detail were the planet only sizable 
enough to furnish it with its necessities. 

So far as we have evidence, life is an inevitable 
outcome of the cooling of a globe, provided that 
globe be sufficiently large. For Hfe did not reach 
this earth from without. No fanciful meteorite bore 
it the seeds which have since sprouted and overrun its 
surface. Meteorites gave it life, indeed, but in the 
more fundamental way in which all nature's processes 
are done, by supplying it with matter only from which 
by evolution life arose. Of this we may be absolutely 
certain from the fact that while meteors were falUng 
upon it in any numbers, they were forming its mass,, 
the full heat of which had not yet been evolved by 
their impact and subsequent condensation. The heat 


that thence ensued was excessive, many fold greater 
than sufficed to kill any germs that might have come 
to it housed in the meteorites themselves. Thus the 
action due the meteorites after :hey came must have 
annihilated any organic possibilities they may have 
brought with them. Those arriving after the heat 
had waned enough to make survival possible found 
life already started, since protoplasm formed the mo- 
ment cooling permitted of it. 

The proof that life was here spontaneously evolved 
appears at every stage in its history, not only in its 
origin, but at every step of its progress upward where 
a marked departure occurs from its previous course. 
It and the environment are observed to have changed 
together. Two short parallel columns, the one show- 
ing the changes that have occurred in the habitat, the 
other those supervening in the habitant, will make 
this not simply clear, but striking. As effective as 
the well-known deadly parallel of oratorical utterances, 
this life-giving one reaches the same certainty through 
the probabilities disclosed. 

Occasion of this vital parallelism occurs at the very 
start. Indeed, we may go back of this and note 
agreement before the start. For until the conditions 
were such as could support life, no life appeared. 
This is the first coincidence. Another follows on its 
heels with the dawn both of conditions fit for some 


existence and of that existence itself. The waters 
were its birthplace. No other portion of the surface 
could then have offered it a home, and nowhere ex- 
cept in the sea is it then found. 

The simultaneity of each new birth and each new 
cradle crops up again when a new field arose by the 
making of the land. As soon as this was suitable, 
plants appeared to take possession of it, and from 
that time on neglected more and more the sea. 

The fourth parallel is found in the significant fact 
that the edible plants and the plant-eaters made their 
debut on the scene together in Miocene times, the 
world having got along without both before that 
epoch. This entry, hand in hand, so to speak, De 
Lapparent, the great French geologist, does not hesi- 
tate to link logically, and to regard the one as the 
necessary complement of the other. If this were not 
the case, there is certainly no reason why they should 
appear at the same instant of time. Food evokes its 
eater in fact as definitely as in phraseology. 

The last of this procession of coincidences, man, 
came on the scene at the time when the cooling of the 
globe rendered his own extension possible at the least 
expense to himself His brain allowed him to take 
advantage of conditions less intrinsically favorable 
than other animals could endure. His mind clothed 
his body and gave him fire, and with these two prod- 


ucts he sallied forth into a world where antagonists 
were chiefly climaticj with which he was fitted to cope. 
Thus all along the line we perceive that life and 
its domicile arose together. The second is necessary 
to the first and the first is always sufficient to the 
occasion. The coincidence of the possibility and its 
seizure, of the posse and the esse^ seems to be a gen- 
eral principle of evolution. Endless variation is con- 
stantly in progress, and this variation takes advantage 
of any opportunity so soon as it occurs. Life but 
waits in the wings of existence for its cue, to enter 
the scene the moment the stage is set. 



Transition. The passing of the supremacy of its own heat, and 

the entrance of the Sun upon the scene as the dom- 
inant power in its life, mark the next stage in a 
planet's history. 

On Earth the transition from self-support to solar 
dependence began with the first symptoms of atmos- 
pheric clearing in the time of the great reptiles. The 
clouds that had veiled the whole Earth in the paleo- 
zoic period then began to dissipate ; though it was 
probably not until much later that the sky approached 
the pellucid character we know. The Earth's own 
cooling thus first let in the Sun. 

That such must have been our Earth's history we 
gather from the other planets ; that it actually was so 
we discover from the records of the Earth itself For 
from the fossils embedded in its rocks we learn that 
when the Triassic strata, more familiarly known as the 
New Red Sandstone, were laid down, gymnosperms, 
cycads, and conifers had replaced the cryptogams of 
the primary age. These plants require more fight 
than ferns. Though technically called flowering 



plants, they yet lacked flowers to catch the eye. Still, 
they demanded more sunshine than their predecessors, 
and thus testify to the purifying air caused by the 
gradual cooling of the surface and the consequent less 
abundant generation of cloud. That the Sun had not 
grown more insistent, but the Earth more open-eyed, 
the latitudinal character of the cooling shows. For it 
was not the absolute lowering in warmth, but the 
zonal differentiation of temperature that then set in, 
which is the noticeable thing. The tropics were as 
before ; the climate was changing slowly toward the 
poles. Climatic zones began to belt the Earth. 

In the next mesozoic division, the Jurassic, the 
corals, by dropping down the latitudes as time went 
on, speak of continued refrigeration. Tropic, tem- 
perate, and frigid regions began to belt the Earth. 
But zones were not yet well established, as the pres- 
ence of the same cycads in Mexico and Franz Josef 
Land suffices to attest. Corals still grew in latitude 
55° N. 

With Tertiary times came in the seasons. Before The 
this the Earth knew them not, though its axial tilt was 
the same as now. Their advent is registered for us 
in the changed vegetation they induced. For their 
presence is witnessed by the coming in of deciduous 
trees, which make their first appearance in its preced- 
ing strata, the lower Cretaceous, and spread and 



flourished in the Eocene, Miocene, and Pliocene eras. 
The northern zones had now grown so cold that vege- 
tation had to hibernate in the winter months. Mean- 
while we mark the palms successively descend the 
parallels in search of heat. In the Eocene — the 
dawn of the recent — already they are lower than in 
earlier epochs ; in the Oligocene, the next age, their 
northern limit is the smaller fifties ; they become 
rarer there in the Miocene ; and in the Pliocene they 
have virtually disappeared from northern Europe. 
With increase in light went hand in hand decrease in 
warmth, which shows that the Earth had been the 
source of the earlier torrid climate. Its seas and con- 
tinents were both cooling off. 

The Sun was slowly asserting his position as the 
great giver of both light and heat, and the world as we 
know it was beginning to be. 

This change in dependence from Mother Earth to 
distant Sun ushered in the reign of beauty in the 
world. We live in the colored supplement of our 
globe's history, the time when the pigments were put 
on ; and this because as fashioner the Sun has replaced 
the Earth. Though they bear no relation to us, the 
gorgeous tints of blossom, butterfly, and bird that so 
delight the eye were called into being by the sunbeams 
themselves ; while the descendants of the plants that 
were beholden chiefly to the Earth — the fungi, mosses. 


and brakes — are sombre browns and greens, and 
flourish only in the shade. A few indeed have 
adapted themselves to the new conditions, but the 
greater part still pathetically cling to the world in 
which they were brought up — a world (except in 
corners) long since passed away. 

Since a general clearing of its sky is a regular step Mars betrays 
in a planet's development, we should expect to find a ^^^^^ 

^ ^ ^ ^ evolution. 

cloudless, transparent air in the case of a planet as 
relatively old as Mars. For thus a body opens its 
eyes to the cosmos. Now, this is precisely what we 
do find. The aspect of Mars shows that it has thus 
waked to the universe about it. In fact, such was the 
very first of its characteristics to be made known to 
the earth, being the one by which the others were re- 
vealed. Without it we had never made acquaintance 
with this other world in space. 

Viewed under suitable conditions, few sights can 
compare for instant beauty and growing grandeur with 
Mars as presented by the telescope. Framed in the 
blue of space, there floats before the observer's gaze a 
seeming miniature of his own Earth, yet changed by 
translation to the sky. Within its charmed circle of 
light he marks apparent continents and seas, now ram- 
ifying into one another, now stretching in unique ex- 
panse over wide tracts of disk, and capped at their 
poles by dazzling ovals of white. It recalls to him 


his first lessons in geography, where the Earth was 
shown him set ethereally amid the stars, only with an 
added sense of reality in the apotheosis. It is the 
thing itself, stamped with that all-pervading, indefin- 
able hall-mark of authenticity in which the cleverest 
reproduction somehow fails. 

In color largely lies this awakening touch that im- 
bues the picture with the sense of actuality. And 
very vivid are the tints, so salient and so unlike that 
their naming in words conveys scant idea of their con- 
cord to the eye. Rose ochre dominates the lighter 
regions, while a robin's-egg blue colors the darker ; 
and both are set off and emphasized by the icy white- 
ness of the caps. Nor is either hue uniform ; tone 
relieves tint to a further heightening of effect. In 
some parts of the light expanses the ochre prevails 
alone ; in others the rose deepens to a brick-red, suf- 
fusing the surface with the glow of a warm, late after- 
noon. No less various is the blue, now sinking into 
deeps of shading, now Hghtening into faint washes that 
in places grade off insensibly into ochre itself, thus 
making regions of intermediate tint the precise borders 
of which are not decipherable by the eye. 

Superimposed upon its general opaline complexion 
are now and then to be seen ephemeral effects. At 
certain times and in certain places warm chocolate- 
brown has been known to supplant the blue. Often, 


too, cold white dots are scattered over the disk, daz- 
zling diamond points that deck the planet's features 
to a richness beyond the power of pencil to portray. 
So minute are they that good seeing is needed to dis- 
close them. It is at such moments that color best 
comes out. To those who know the sun only as 1 
golden and the moon as white, even in its color 
scheme Mars would stand forth a revelation. 

It is easy to travel in thought over the strange 
land thus displayed below you. For though you 
gaze up into the sky, you still look down upon its 
ground, and follow consciously or unconsciously the 
configuration of its surface with cartographic eye, now 
led by some apparent bay to run with it up into the 
continent, now witched by the spirit of exploration 
toward some island, as it seems to be, set remote in 
the midst of the sea. But whether you purpose it or 
not, nature, taking the matter out of your hand, de- 
cides it for you. For presently you perceive your 
point of view not to be quite what it was. The bay 
in question, as well as the island, has slightly changed 
its place upon the disk, while the two have kept their 
mutual relation unaltered. A few minutes more and 
the shift has increased, and then you become aware 
of what is taking place : this other world is turning on 
itself, as turns our own, rotating from west to east as 
it rolls along its orbit about the sun. 


Up over the rim of the disk rises a marking, to 
swing in time across the centre, and then on out of 
sight round the other Hmb. The one horizon marks 
the sunrise-Hne upon the planet, the other the sunset 
one, and in its course between the two the place has 

Two Views of the Solis Lacus Region of Mars, One Hour apart, 
July 26, 1907 (the One to the Left the Earlier), showing the 
Rotation of the Planet. North is at the top 

had its Martian day. Unsuspectedly, but no less 
potently for that, the act of such withdrawal only whets 
curiosity the more. What perchance might have 
wearied had it remained forever there, gains an added 
glamour from the fact that it is gone. But, more than 
this, it gives an earnest of yet further fields to be 
explored. From the circumstance of turning comes 
promise that other regions will later be displayed, and 
as the observer watches, the predicted comes to pass. 
One longitude after another turns the corner, rounds 
into view, and slowly swings into the meridian plane. 


Objects, grown familiar, give place to others that are 
new. Sitting alone in midnight vigil in his silent 
dome, the astronomer thus mutely circumnavigates 
another world. 

The cloudlessness of the planet's sky alone makes 
such travel possible. Were it not for the unobstructed 
view, exploration of the sort would be out of the ques- 
tion. Were Mars not an old planet, corroborating by 
absence of cloud the general course of planetary devel- 
opment, our knowledge of it had been slight. To 
begin with, its lack of covering enables us to mark 
the permanency in place of the planet's features, and 
from such permanently to time the planet's axial 
rotation. This gives us knowledge of the planet's 
day and furnishes means to measure it. This day 
proves to differ in duration little from our own, 
being 24 hours, 40 minutes long, instead of 24 
hours. In the next place its scantiness of atmos- 
pheric apparel discloses the tilt of the axis to 
the planet's orbital plane, a relation which causes 
the seasons of the year. Now the Martian tilt, 
as well as the Martian time of rotation, turns 
out to be singularly like our own, being, in fact, 
24° * as against 23^° for the Earth. Thus the 
Martian seasons counterpart ours. The year of 

* Still later measures at Flagstaff make this even smaller, 23° i 3', — or actually a 
little less than ours. (See note 18.) 


Mars, however, is twice ours in length, which, joined 
to great eccentricity of orbit, gives it diversifiedly long 
seasons. Thus, in the northern hemisphere, spring 
lasts 199 days, summer 183, autumn 147, and winter 
158, while in its southern hemisphere the figures stand 
reversed. The numbers have more than academic 
importance, for absolute length is as vital a factor in a 
season's influence as the fact of the season itself. 
Much may be brought to pass in twice the time which 
could not develop in the shorter period. And it is 
not a little interesting that precisely this possibility 
actually turns out to be vital in the vegetative economy 
of the planet's year. 
The thin Absencc of cloud speaks, too, of the thinness of 

the planet's air,^^ of which we have other evidence as. 
well. Perhaps the best proof of a relatively thin air 
is the lack of intrinsic brilliancy of the Martian disk, 
its "albedo," as it is called. This is only 27 per cent of 
absolute reflection, as against 92 per cent for Venus. 
Now, a thick air, even if clear, — indeed, because clear, 
— would cast a luminous veil over the planet's face 
due to dust or vapor, as it does with Venus, dimming 
its features. Such is not the case with Mars. 

Of twilight, therefore, there should be less, and 
certain observations made at Flagstaff in 1894 seem to 
prove this. The refractive medium of air which on 
Earth calls the Sun earlier in the morning, and keeps 

of Mars. 



The North Polar Cap of Mars at its Least Extent 

him up later at night than would otherwise be the 
case, is not so potent on Mars. Day there enters with 
greater abruptness, and lapses into more sudden dusk. 
Then comes a night when the stars stand forth with 
an insistency unknown on earth. 

That some air exists is, however, patent, both directly 
from the limb-light that fringes the circlet of the disk 



The polar 
caps of Mars. 

and inferentially from the changes that we mark in 
progress on the planet's face. For change of itself 
impHes an atmosphere. 

First of the phenomena to betray this air were the 
white caps that bonnet the Martian poles ; for in the 
person of these patches transformation was first recorded 
upon the Martian disk. Their position, together with 

The South Polar Cap of Mars at its Greatest Extent 


their seasonal wax and wane, pointed them out for 
polar snows gathered during the Martian winter and 
melting with the Martian spring. 

That the polar caps are composed of snow, or, 
rather, hoar-frost, suggests itself to any one who 
carefully scans the planet. But to prove it was not 
so easy. Fortunately, 
a phenomenon which 
accompanies it turned 
out, when rightly 
reasoned on, a touch- 
stone to its character. 
As the cap melts, it 
is seen to be girdled 
about by a dark-blue 
band, deeper in tone 
than any other blue- 
green area on the disk. This belt developed the 
peculiar property of retreating with the cap as the 
latter shrank, maintaining throughout its attendant 
post. The phenomenon was first seen by Beer and 
Madler, but it was not till 1894 that its significance 
was seized. 

Clearly the outcome of the melting cap, it disposed 
by that fact of the suggestion that the caps might be 
soHd carbonic acid that freezes at 109° F. into a sub- 
stance not unhke snow. For carbonic acid, under 

Drawing of Mars, April 8, 1907, 

DLES THE Snow During its Melting 



pressures of one atmosphere, or less, such as would be 
the case on Mars, passes instantly from the gaseous 
into the solid state. Not so water-vapor. Here, 
then, was a telltale bit of behavior. The blue belt 
proclaimed the presence of a liquid. Thus carbonic 

From drawings, July 20 and 22, before and after the event. 
Early Winter Snow-storm in the Northern Hemisphere of Mars, 
1907 (North AT the Bottom) Martian Dates : October 22, Left- 
hand Drawing; October 23, Right-hand Drawing 

acid could not be concerned, and the substance com- 
posing the caps was therefore snow. For no other, 
that we know of, dons their snowy aspect with change 
of state. 

The behavior of the cap thus affords intrinsic proof 
of its constitution. Since this was determined, another 
line of argument has given extrinsic evidence of the 
same thing. This is the evaluation of the surface 
temperature of the planet recently made for the first 
time with any approach to precision. 


The stronghold of doubt as to the habitability of The question 
Mars has always been the difficulty of accounting for onMaT^"*^^ 
a temperature there high enough to support life. 
From its own bodily heat at the present time the 
planet itself, like our own earth, can contribute to the 
surface temperature no appreciable amount. The 
necessary caloric must all come from the sun. Now, 
because the planet was half as far again from the sun 
as the earth, and because light and heat diffuse in- 
versely as the square of the distance, — a candle two 
feet away giving only one-fourth the light of one a 
foot off, — it was supposed that Mars must receive 
only four-ninths the warmth that the earth gets, which 
would render its temperature terribly low. 

But the receipt of radiant energy is not so forth- 
right as this. To begin with, the bundle of rays from 
the sun striking the planet is subject to two adventures 
at the very threshold of its planetary career. A part 
of it is at once reflected back into space from the body 
it strikes — from the air first, then from the planetary 
surface. But the reflected light or heat does not go to 
warm the body at all. Strange to say, this important 
fact had never been taken into account until the 
present investigation of the subject, which led to a 
completely different outcome from what had previously 
been supposed. Too technical for exposition here, 
one or two points in it may be mentioned. First, the 


proportionate amount of the reflected light-rays which 
reach an observer stationed on another planet measures 
the relative brightness of that planet as seen by him. 
This per cent per square unit of surface at distance 
unity is what is called the planet's albedo. Now the 
albedo of the different planets has been found by more 
than one observer from investigations unconcerned 
with our present subject, the only gap in the series 
being that of our own earth. The latest determina- 
tion by Miiller is : — 

Mercury 0.17 

Venus 0.92 

Mars 0.27 

Jupiter 0.75 

Saturn (Struve) 0.78 

Uranus 0.73 

Neptune 0.63 

Our own earth's albedo is lacking from the table 
because we cannot see ourselves as others see us, and 
are consequently somewhat in the dark as to our own 
appearance. By suitable deduction, however, from the 
brightness of sunlight at different altitudes above the 
surface of the earth, it is possible to get some idea of 
it, and from this a modest estimate puts it as at least 
.75. So that we are not so dull as we thought. 

Thus we get the amount of radiant energy received 


from the visible part of the sun*s rays. There are also 
rays too long to be perceived by our eyes, and these 
must also be considered in a determination of the 
whole. The bolometer invented by Langley enables 
us to do this, and so to obtain the fraction of the 
total incident energy which goes to warm the body. 
In the case of the earth it proves to be 41 per cent 
of the whole ; and in the case of Mars, 60 per cent. 
Here, then, we have at once a serious modification 
of a calculation based on distance alone. 

But this is not all. The clearness of the Martian The dear 
sky comes in to abet the greater transmission of its 
air. From dawn till dusk, day after day in the sum- 
mer season, and largely in winter, the sun shines out 
of a heaven innocent of cloud. No shield of the 
sort, and only a little screen of air, tempers its 
beams to the soil held up to it. Such an exposure 
far exceeds anything we have on earth ; for with us, 
even in the tropics, clouds gather as soon as the 
heating grows excessive, and cool the air by plumps 
of rain. 

How much this means to a planet as far away 
from the sun as Mars, will appear if we consider 
what in this respect is the condition of the earth. 
Over the earth as a whole, the proportion of actual 
to possible sunshine for the whole year is 50 per 
cent. That is, the sky is such that the sun shines 


only half the time it might were there no clouds to 
screen it. 

On Mars the spring mistiness at the borders of 
the polar cap is the only veiling the surface knows, 
with the result that the percentage of sunshine 
throughout the year is 99 per cent of the utmost 
possible. This is somewhat reduced by the fact 
that some light and heat of course is let in by the 
clouds — and is kept in better, too. 

Taking these different data, and using the most 
recently determined relation of radiation to temper- 
ature (that of Stefan, which has been independently 
deduced theoretically by both Boltzmann and Ga- 
litzine), we find that the mean temperature of the 
surface air of Mars should be about 48° F. We 
must not place too much credence in the actual fig- 
ures, for our knowledge of the laws of atmospheric 
retention of heat is very uncertain, but the research 
is enough to show that the above result is much 
nearer the truth than the terribly cold ones. That 
of the earth is only 60° F. ; so that the mean cli- 
matic warmth of the two planets is not very unlike, 
and far within the possibilities of life for both.^^ 

But the circumstances are even more favorable to 
Martian life than this. For man does not live by 
mean annual temperatures alone. In fact neither 
he nor other animals in our temperate zones pay so 


much heed to yearly averages as is sometimes sup- 
posed. Much more to the point with them is the 
mean summer warmth they experience. 

NoWj in the summer-time, — that is, all the way Summer and 
from some months after the winter solstice to some ^"^"^ ^"^" 


months after the summer one, — more heat is ab- 
sorbed daily from the sun than is radiated out to 
the stars at night. The surface temperature is then 
constantly rising ; a fact patent when one stops to 
think of it in this way, since June is warmer than 
March, but that this means that the day's gain ex- 
ceeds the night's loss is commonly lost sight of 
The fact is pertinent to our present inquiry. For 
the daily increment continues for half the year, and 
the Martian year is twice our own in length. Its 
total gain in summer over the mean would, other 
things equal, rise to something like twice our own. 
Instead of a temperature lift of 30°, as with us, on 
Mars it might well be 50°, in spite of the thinner air. 
That a thin air is compatible with great surface 
heat the latest and most authoritative measures of 
the heat of the moon's surface during the lunar day 
interestingly corroborate. These measures are those 
of Professor Very. With great care and thorough- 
ness this excellent investigator experimented on the 
amount of heat radiated by different parts of the 
moon at different times of the lunar day. He con- 


tinued the work Langley had begun to a much 
finer point of precision. It used to be thought that 
even at lunar midday the temperature of the moon's 
surface must be below freezing because of its lack of 
a retaining blanket of air. Very's latest conclusions' 
in the matter put a quite different aspect upon it. 
In a letter of his to the writer he sums up his results 
as follows : — 

When the sun rises, no matter in what latitude, it is cold. I do 
not venture to say how cold, but below the freezing-point. Not 
until the sun has reached an altitude of 1 5° in middle latitudes does 
the temperature get above freezing. Then the heat mounts rapidly 
until at the end of the first week of sunshine in dry regions near the 
equator the rock surface is as hot as boiling water. As midday ap- 
proaches at the end of the second week, the scorching rocks attain 
a temperature full 80° centigrade above the boiling-point of water 
in regions under a vertical sun (356° F. ). Having once become 
heated, the rocky surface retains its heat to a great extent far into the 
afternoon, the curve of falling temperature being perhaps a day and 
a half of our time out of symmetry. Toward the end of the lunar 
afternoon the fall of temperature is very rapid, and before the sun 
sets, frost prevails, or at least temperatures which produce frost 
wherever there is water-vapor to make the article which we call 
*' hoar-frost.'* 

And this great heat occurs where there is virtually 
no blanket of air ; and, what is even more striking, 
its temperature maximum is not attained till a day 
and a half after its greatest receipt of sunshine. 


Now, when we turn from deduction to the picture Aspect of 


the planet presents, which, after all, is entitled to corroborative. 
some consideration in statements about itself, we 
confront what certainly seems a body in fairly easy 
circumstances of temperature. In its summer the sur- 
face lies fully exposed to our gaze, and it assuredly 
is not suffering from wholesale glaciation. On the 
contrary, the phenomena point to something quite 
the reverse. For weeks its arctic regions up to 86° 
and 87° N. latitude are certainly above the freezing- 
point, since the snow disappears. Probably they are 
far above it, for in the polar caps we then behold a 
shrinkage much greater than anything we similarly 
experience on earth, part of which is due to less 
depth of snow, but showing also that it is relatively 
warmer there than here. Lower down the disk, 
toward the equator, great dust-storms, like the si- 
mooms of our Sahara, sweep over portions of it at 
times, hundreds of square miles in extent, convey- 
ing to the onlooker anything but a sense of chill.^^ 
In winter the opposite state of things prevails. A 
good sixth of the whole surface goes into winter 
quarters as each autumn draws on. It stays so, too, 
for some eight of our months on end, not to emerge 
till the next Martian spring. A winter on Mars in 
high latitudes has a polar complexion to it not wholly 
pleasing to contemplate. 


But the idea that such a winter's counterpane be- 
tokens more than hibernation, and in any sense hazards 
the existence of Hfe, a moment's thought on our own 
. conditions of Hving will suffice to dispel. The great 
nations of the earth, with scarce an exception, live half 
the year in the earth's north polar cap, buried in snow 
and hidden the greater part of the time from visual 
communication with outside space. If Martian phi- 
losophers are of the pattern of some earthly ones, they 
must incontrovertibly prove to their own satisfaction 
the impossibihty of our existence. Nevertheless, from 
the fairly successful way in which we manage to sur- 
vive in open contravention of philosophy, we see that 
it is not necessary even to suppose hibernation, fea- 
sible as nature finds that to be with insects, fishes, and 
beasts, in order to tide an animal over from one period 
of warmth to the next. An organism with or without 
what we are pleased to call human intelligence is quite 
capable of submitting to conditions which would, if 
permanent, prove destructive to life, and of biding its 
time to a more propitious season. 
Summer the For, thanlcs to rcccnt research, we now know that 

with animals generally it is the summer temperature, 
not the winter one, that decides the question as to 
whether life shall exist. An able investigation of the 
United States Government Zoologist, Dr. Merriam, 
made upon the region of the San Francisco peaks, in 

life season. 




^^^ spruce zone |%^^ pine zone | 1|||||||| desert 

Merriam's Map of San Francisco Mountain and Vicinity, Arizona 
Published in " North American Fauna, No. 3." 


1889, brings this point out with great acumen. Its 
pertinency to the problem before us commends it to 
reference here. 

In geographic and climatic position combined the 
San Francisco Mountains of northern Arizona are 
among the most interesting animal and vegetal habitats 

The San Francisco Peaks 

of the globe. They are what is left of a great crater of 
Tertiary times, which, rising out of the plateau north 
of the Arizonian desert, tower to 12,630 feet of alti- 
tude. The massif of this once volcanic cone sup- 
ports now many square miles of forest on its flanks, 
and its plateau base is clothed with pine ; while girdling 
it about, and cutting it off like an island from other 



vegetation, stretch the arid wastes of the great Ameri- 
can desert. 

This floral island is remarkable for being banded by Zones ofvege- 
successive zones of trees, each distinctive and exclusive, !,^''°'l ° ^ ^ 

■' ' San Francisco 

and giving place the one to the other solely according Mountains. 






■— - 

Arizona Desert View 

to elevation. Starting from the desert forty miles 
away, where sage-brush and cacti alone succeed in 
managing an existence, the traveller enters at an eleva- 
tion of a mile and a quarter above the sea the initial 
zone of scrub. Stunted at first, clumps of dwarf juni- 
per — cedars, as they are locally called — make their 
appearance, and grow in size and vigor as he continues 



to ascend. With them are soon associated another 
form of juniper and the pinon, a small tree from twenty 
to thirty feet in height. At about 7000 feet he en- 
counters the Finns fonder osa^ to which the juniper and 
pinons then give way, and the whole aspect of the 

The Douglas Fir 

tree vegetation changes. Here the stately pines pos- 
sess the land alone, save for a few white oaks on the 
edges of the mesas. At 8500 feet the yellow pines 
disappear, to be succeeded by the Douglas fir, the 
Rocky Mountain pine, and the beautiful trembHng 
aspen. At 9500 feet this set of trees gives place to 
yet another, and the traveller enters the western white 
spruce zone, associated with which is the fox-tail pine. 


the needles of which startHngly suggest a fox's brush. 
At 10,500 feet these trees dwindle to dwarf specimens 
of themselves, until at 12,000 feet they entirely lapse, 
and naked rock stretches supreme to the summit. A 
climb of 8000 feet from 5000 to 13,000 of elevation 
has carried the observer through six zones of absolutely 
distinct tree life, counterparts of the tropic, the tem- 
perate, the Canadian, the Hudsonian, the Arctic, which 
he would have traversed had he journeyed from the 
foot of the mountains northward to the pole. 

To the higher slopes of the mountain every summer 
deer troop from the lower plateaux where they have 
passed the winter, to stay at these heights until 
October's cold drives them down again ; while upon it 
all the year round are to be found bear, which also go 
up and down with the change in seasons. In addition 
to these are wildcats and mountain lion, besides a 
host of smaller mammals, squirrels, gophers, and the 

Merriam camped upon the peak in July, 1889, and Summer tem- 
studied the habits of the animals at high elevations ^[nX^e If^ 
during the summer months, comparing the various ^'^^• 
genus and species found there with those known 
northward in the world. Among other interesting re- 
sults he found that the survival of species is determined 
not by the mean annual temperature of the locality or 
by the winter minimum, but by the maximum temper- 


ature prevailing during the short summer months. It 
is in this season that the animals bring forth their 
young, and his study showed that if they were suffi- 
ciently warm during the reproductive season, cold dur- 
ing the rest of the year mattered not. At the worst 
they hibernated. Here, then, the fact of a few warm 
weeks made life possible, outweighing the impossibility 
of all the other long, cold, forbidding months. Fur- 
thermore, what is important to our present discussion, 
Merriam found that temperature was more potent than 
humidity, so long as they had any water at all. 

This point in animal history has immediate bearing 
upon the habitability of Mars ; for the Martian sum- 
mer is twice as long as ours, and, as we have seen, the 
probable acme of warmth attained in it is by no means 
small. It is by these attributes of its climate, and 
not by its mean annual temperature, or by the great 
cold its surface very possibly experiences in winter, 
that its ability to support life must be judged. 

Another point the presence of the animals on the 
San Francisco Mountains serves to bring out — their 
indifference to thinness of the air. The creatures 
which dwell on the peak, or which visit it as a summer 
resort, are members of the same species whose natural 
home is at sea-level farther north. The deer are such 
as one finds in the northern part of the United States ; 
the bear are the same as those inhabiting the forests of 


Canada and Labrador. Altitude takes the place of 
latitude in sufficiently cooling the habitat to their ac- 
commodation. But it does this at the expense of air. 
On the peak they dwell at elevations of 10,000 feet, 
where the barometer marks only 18 inches, instead of 
the 30 to which their relatives are accustomed. Yet, 
in spite of living in atmospheric penury on the man- 
sard roof of the world, — for the mountain here is 
steep, — they suffer no inconvenience, and seem totally 
unaware that they are doing anything peculiar. Nor 
have they seemingly changed in organic or even in 
functional development. With the deer the lack of 
special adaptation is equaled only by the lack of con- 
scious absence of it, and the animal is as much at home 
as in the timber of the Minnesota woods. 

That thinning of the air proves no bar to a species, 
provided other conditions are the same, is further 
shown on the high lands of the western United States. 
The meadow-larks of the great plains rise with the 
surface into the parks of the Colorado Rockies, with 
an altitude of eight thousand feet, and are there as 
much acclimated as at two thousand in the Kansas 

Now, if such a barometric range can be borne semi- 
annually without special modification by the organism, 
how much more may not be accomplished by accom- 
modation, given a sufficiency of time ? Men who first 


pitiably gasp, learn to endure, and finally, embrace, a 
life of elevation. Quito, at ten thousand feet, has a 
population who live as easily as their relatives at sea- 

Plateaux Icvel. 

hotter than Owing to the thinness of the air, it has been cus- 

peaks at a 

like elevation, tomary to Hken the conditions on Mars to those upon 





46^ North Latitude. 29° North Latitude^ 16'-' bouth Latitude. 

From Geikie's " Elementary Lessons in Physical Geography." (The Macmillan 


Vertical Distribution of Climate on Mountains, showing how 
Land-masses raise the Temperature 

our highest mountain tops, where life finds it impos- 
sible to exist. But the analogy is misplaced. Mars, 
with its level surface, is more like some vast plateau. 
Now, that the temperature of a plateau exceeds that 



of a peak at the same height, table-lands on the earth 
make evident. Humboldt cited the Himalaya. On 
the north side of this great range, both snow-line and 
timber-line are three thousand feet higher than on the 
south side, a climatic lift brought about by the 
Tibetan table-lands on the north; and this in spite 
of the contrary effect of slope exposure. 

But we may get instances nearer home. In scan- 
ning Merriam's chart Lowell was struck by a fact 



After a plate in "North American Fauna, No. 3," U. S. Dept. of Agriculture, Division of 
Ornithology and Mammalogy, by Dr, Merriam. 

Diagrammatic Profile of the San Francisco and O'Leary Peaks, 
FROM Southwest to Northeast 

The diagram shows the several life zones and the effects of slope exposure, but 
also shows what is unnoticed by the monograph, the effect of a plateau upon 
hfe. The location of the Lowell Observatory is indicated by the star. 

unmentioned by Merriam. Superposed upon the 
more evident dip of the zones down from the south- 


west to the northeast a divergence in this dip may be 
recognized, the dip increasing as the zones mount. It 
at once occurred to him that this must be due to the 
mass of land upon which each rested. That, in short, 
the isoflors rose relatively to the north because of the 


>^^A.: f>.,Au.:.:.7f!cu 


„v- wa\ 



•^.;^ U§^ 

■" ^^ / 



^-~— - 


'^-^ -•"" 

d .2 

^„\- J.-».^ 


Showing Effect of Plateau Elevation on Tree Zones — 
Less Elevation 

higher plateau base there. To test this he made a 
series of camping trips this last summer, 1907, on 
and about the peaks, measuring, with an aneroid 
checked by trigonometric survey, the heights at 
which the several species of trees grew and from his 
data laying down the isoflors. The outcome was more 



striking when thus carefully done than it had been 
in Merriam's map, and quite conclusive as to cause. 
It is here presented to the reader in a series of charts. 
In these charts not only does the dip decline less 
the nearer the tree zone stands to the plateau, but in 

A,40/.fur _ G 




-'. s'- 



4'vv.^.^ _ 





j,zt..l:. ■ 



X.A "... 


■ /"\ 

»^ / 




y... /^^-" 

' ■■-— 





. .'^^, 


,4./-c.^/:- --/ 

.., r/ 

1.1 1 


"i::Z^-'- ■/ '■-■ 

■ ". l 

Showing Effect of Plateau Elevation on Tree Zones- 
Greater Elevation 

the nearest of all, the pine zone, the influence of the 
northern plateau is actually sufficient to counteract 
the opposite effect of slope exposure and cause the 
isoflor to rise toward the north. 

The explanation of the matter is not far to seek. 




Yi^^o p^ 

■^^ 'is So //• 





Diagrams of Two Craters showing Greatest Cold N.N.W. 

Each bit of plateau helps warm its neighbor, and so 
keeps a heat that else had radiated away. So much 
for the effect of but a small plateau. If even a lim- 


ited area of high ground can so far ameliorate the 
temperature, how much more would be accomplished 
were it to become world-wide ? 

That we do not find animal and vegetable life at 
the tops of our highest mountains is due to other 
cause than elevation ; namely, to the restricted nature 
of the habitat upon the pointed needle of a peak, sep- 
arated by impassable gulfs from other equally limited 
areas. The animal has no range of forage and no 
chance of commerce with its kind. This is one rea- 
son for the absence of life upon isolated pinnacles. 
Yet even so its presence proves surprising. On the 
very pinnacle of the San Francisco peaks, at 12,630 feet, 
the tracks of a chipmunk showed clearly in the snow 
on the occasion of its ascent upon October 15. Another 
exterminating cause is the wind that of necessity always 
draws over a peak at the slightest provocation. The 
consequent drain upon an animai's own heat when 
made under low temperatures is fatal to life. Man can 
endure 70° below zero F. if the air is still, but perishes 
at 40° below under the least wind. Even a breeze, there- 
fore, is equivalent to a fall of 30° F. in the temperature. 

By both temperature and appearance, then, water- water-vapor 
vapor proves a constituent of the Martian atmosphere. '" 
Now, the vapor of water is a light gas, the lightest of 
the constituents of our own air, and, in consequence, 
by the laws of gases, among the most difficult for a 


planet to retain. Its presence, therefore, in a planet's 
gaseous envelope is of the nature of a guarantee that 
less volatile associates are also to be found there. 
These, in an increasing order of weight, are nitrogen, 
oxygen, and carbonic acid gas. So we may con- 
clude that these are probably also to be found on 

But we are far from having to rely upon such infer- 
ence, well founded in principle as it is, for our knowl- 
edge of the existence of these important gases in the 
atmosphere of the planet. Modern observation of a 
quite unrelated class of features puts their presence 
there upon a secure footing — a planting on the prem- 
ises of both feet instead of one by the logical body of 
fact ; and that, too, by reason of a descent from the 
air to the solid surface of the ground. It is the now 
recognized constitution of one of the two great classes 
of markings that diversify the disk which has given us 
the necessary information. The blue-green regions 
have proved themselves the sibyls in the case. 

In form first, in color subsequently, the blue-green 
areas commended themselves as seas and oceans to the 
mind of the early areographers. Even Schiaparelli so 
considered them. Nor at that stage of acquaintance 
was the characterization at all far-fetched. But as 
these seeming seas were better scanned, differences of 
tint became apparent in them. This should have 


shaken belief in their character, but so tenacious is 
an idea when once it has taken root that the dis- 
covery awoke no doubt. The oceans were merely 
spoken of as shallower in some places than in others, 
as if thousands of square miles of water so few feet 
deep that the bottom showed through did not of itself 
need explanation. 

Next, these very differences showed variation. 
Areas as large as Great Britain, and often very 
much larger, would lighten in the course of a few 
weeks in a perfectly unmistakable manner. Indeed, 
the greater part of the whole southern hemisphere of 
the planet would thus doff one tone, and even tint, 
to don another at surprisingly short notice, and this 
without anything approaching a correspondingly sizable 
darkening elsewhere. 

When we set ourselves to consider the matter in the 
light of what was seen, we perceive that such absence 
of reciprocity is fatal to the theory of a liquid film. 
For were the transformation some subtle shift of sub- 
stance, what one part lost, another must have gained. 
Either transferred as water elsewhere or wafted away, 
to be deposited as snow about the pole, the thing 
should still be somewhere in the planet's aqueous 
economy. Yet neither of these counterbalancing ef- 
fects was perceptible. As water it had vanished, and 
the polar caps were not increased. 


Vegetation Left, thus, without a marine character to their name, 

we are led to inquire what these patches, which both 
in form and color ape water, can in reality be. If the 
great blue-green regions be observed at intervals of a 
few weeks, and the aspects they successively present 
be recorded in drawings, intercomparison suffices to 
make evident that the metamorphoses they experience 
are periodic, and the period that of the planet's year. 
The changes, then, are seasonal in cause. That is, 
they depend upon the sun. And in proof of the 
relation, their fading out is found to occur in winter, 
when the sun is least operative, and their greatest 
evidence in midsummer, when the sun is locally most 

Now, there is only one thing, so far as we know, 
thus obedient to the sun and indicative of its subser- 
viency by a change of hue from blue-green to ochre, 
and that is vegetation. Both colors are self-accusa- 
tory. The first speaks of verdure in its prime, the 
second of the change of the leaf to the sear and yellow 
stage, just as it takes place in our own foliage on the 
approach of autumn's frosts, indicating that its course 
is run. Not otherwise could we observe it from 
space, should we mark our own familiar earth change 
color when its season's work was done. 

Vegetation thus vouched for, the constitution of the 
air becomes more certain. Besides water-vapor, oxy- 


gen and carbonic acid gas must both be present, and 

undoubtedly nitrogen, too, since in the matter of 

density it holds an intermediate position. To find ■ 

that the Martian air is made up of our old familiar ! 

friends in the matter of gas is an important step to i 

acquaintance with what goes on upon that other world. ! 

Though we are indebted for our knowledge of its 

existence to the vegetation, which is visible while the > 

air is not, it is in fact the vegetation that is indebted ; 

to it for being able to show at all. 1 

Of organic existence there the main, or natural, fea- Mode of 
tures of the planet's face could not be looked to for ofufg^ 
more disclosure. Indeed, the surprising thing is that 
they should have disclosed so much. That the com- ^ 

ing and going of vegetation should be visible across < 

the thirty-five million miles of space to which at its i 

least the gap separating us from Mars is reduced, is 
little short of marvellous. As for a direct view of any 
animal life the planet might support, it would be out j 

of the question. In a very different manner would j 

this reveal itself Not through its body should we j 

be ware of it, but through manifestation of its mind. \ 

By the material changes in the surface of a planet 
wrought by the dominance of his mind over matter 1 

would the other world-worker stand confessed. This | 

we shall reahze if, from the point we have gained in ; 

establishing the probable existence of such life, we go 


on to consider its probable character. Such can be 
done by reviewing the experience of our own planet. 

From what has taken place on earth, we see that 
cooling and complexity of organism have advanced to- 
gether. Life originated here as soon as the tempera- 
ture fell below the boiling-point, and it started in 
water, the liquefying of which out of steam gave it at 
once an essential factor of its substance and an environ- 
ment of the most easily satisfying kind. 

An upward step in evolution occurred when life 
stepped out upon the land. While less directly 
favorable to life, the land was fraught with more pos- 
sibilities for organisms capable of turning them to 
account. Brain was needed, and brain evolved. 

Brain, indeed, now became the chief concern of 
nature. The character of the habitat undoubtedly 
brought this about through the prizes it offered the 
clever, and the snuffing out to which it consigned the 

For long the animal remained thus the creature 
of its environment, its view restricted in both time 
and space. Greater possibilities came in with man. 
Doubtless his was no very dignified entry, though 
something better than on all fours. Brain now finally 
distanced brawn, and even in his savage state man 
became a being that others feared. From thus stand- 
ing primus inter pares, he soon developed into first, 


" with the rest nowhere." Fire and clothes raised him 
to some independence of his surroundings, and slowly 
he began to take possession of the earth. His breech- 
ing, the putting on by the race of the toga virilis, was 
both an incident of his rise and part cause of it as well, 
for it made him superior to climate. But the fertility 
of brain, however humble in its beginning, which sug- 
gested the means of protecting the body, devised the 
methods by which he was to subjugate the earth. 

For some centuries now this has been his goal, un- 
conscious or confessed. The true history of man has 
consisted not in his squabbles with his kind, but in his 
steady conquest of all earth's animals except himself. 
He has enslaved all that he could ; he is busy in ex- 
terminating the rest. From this he has gone on to 
turn the very forces of nature to his own ends. This 
task is recent and is yet in its infancy, but it is destined 
to great things. As brain develops, it must take pos- 
session of its world. 

Subjugation carries its telltale in its train ; for it 
alters the face of its habitat to its own ends. Already 
man has begun to leave his mark on this his globe in 
deforestation, in canalization, in communication. So 
far his towns and his tillage are more partial than com- 
plete. But the time is coming when the earth will 
bear his imprint, and his alone. What he chooses, 
will survive ; what he pleases, will lapse, and the land- 


scape itself become the carved object of his handi-^ 

Equally applicable is this deduction to planets other 
than the earth. Instead of its being true, as a recent 
writer remarked, that "we cannot expect to see any 
signs of the works of inhabitants of Mars if such ex- 
ist," precisely the opposite is the case. Until the ani- 
mal attain to dominance of his world, his presence on 
it would not be seen. Too small in body himself to 
show, it would be only when his doings had stamped 
themselves there that his existence could with certainty 
be known. Then and not till then would he stand 
disclosed. It would not be by what he was, but 
through what he had brought about. His mind would 
reveal him by its works — the signs left upon the 
world he had fashioned to his will. And this is what 
I mean by saying that through mind and mind alone 
we on earth should first be cognizant of beings on. 



STUDY of Mars proves that planet to occupy 
earthwise in some sort the post of prophet. For, 
in addition to the side-lights it throws upon our 

Comparative Sizes of the Earth and Mars with the Polar Caps 
OF Both in their Springtime. 

past, it is by way of foretelling our future. It enables 
us to no mean extent to foresee what eventually will 
overtake the earth in process of time ; inasmuch as 
from a scrutiny of Mars coming events cast not their 
shadows, but their light, before. 

It is the planet's size that fits it thus for the role 
of seer. Its smaller bulk has caused it to age quicker 
than our earth, and in consequence it has long since 


passed through that stage of its planetary career which 
the earth at present is experiencing, and has advanced 
to a further one, to which in time the earth itself must 
come, if it be not overwhelmed beforehand by other 
catastrophe. In detail, of course, no two planets of 
different initial mass repeat each other's evolutionary 
history ; but in a general way they severally follow 
something of the same road. 
Mars has lost It is in the matter of water that Mars stands forth 

its oceans. - , , . . - . . 

as a prophet, and this in two ways : as polar ice and as 
oceanic expanses. 

The first of these has reference to our own glacial 
epoch, a geologic phenomenon the strangeness and 
seeming unaccountableness of which has grown as 
scientists have contemplated it with more care. That 
vast areas of the earth's northern hemisphere, and of 
the southern, too, were at times covered by a continu- 
ous ice-sheet is a fact remarkable enough in itself, but 
grown still more curious from the difficulty experi- 
enced in assigning it adequate cause. Cosmic cooling 
of our planet will not explain it, certain as that cooling 
is ; for the refrigeration was partial, and recurrent as 
well. Croll tried to account for it, but ingenious as 
his idea was, it will not hold water — in the shape of 
ice — in the form in which he put it, and it is now 
virtually abandoned by geologists, although it contains 
considerable truth. 


Now, it is not a little interesting that Mars should 
have something to say upon the subject — something 
which throws light upon the phenomenon as a general 
planetary process, and specifically upon its occurrence 
on our earth. It is because Mars happens to present 
precisely the astronomic conditions which form the 
basis of Croll's theory, and at the same time shows 
the exact opposite of the prescribed results, that its 
evidence is valuable. 

The relative length of a planet's seasons are deter- 
mined by the elliptic orbit the planet pursues. If the 
axis be so tilted that summer of one hemisphere occur 
when the planet is nearest to the sun and therefore also 
moving swiftest, that summer will be short and hot, 
while the corresponding winter will be long and cold. 
This hemisphere will have seasons of extremes ; the 
other reversely will have long, cool summers and 
short, warm winters or seasons of means. The greater 
the eccentricity of the orbit the greater the accentua- 
tion between the two hemispheres. 

Glaciation would result from a greater deposition of 
hoar-frost or snow in winter than the succeeding 
summer's sun could melt. A lengthening of winter 
at the expense of summer would seem, therefore, able 
to bring it about. Now, a greater eccentricity in the 
orbit of the earth than is the case to-day existed in the 
past, and would produce just this effect. So Croll 


argued that it had done so. Unfortunately for the 
theory. Mars moves now in an orbit more eccentric 
than that of the earth ever can have been, and the 
nearest approach of the planet to the sun occurs, too, 
not far from the summer solstice of its southern hemi- 
sphere, yet that hemisphere which should show gla- 
ciation not only does not, but comes farther from 
doing so than the other. For while the northern cap 
diminishes from 78° across to 6°, the southern 
dwindles from 96° to nothing. This shows that 
while for various reasons the longer winter results in 
a greater deposition, the shorter but hotter summer 
of its hemisphere more than melts it away. 

Now, if we increase pro rata the precipitation over 
the whole planet, we perceive that the extent of the 
southern cap at its greatest will still more outdo the 
northern one, and as the melting capacities of the two 
summers are approximately constant quantities, a time 
will come when the remains of the southern cap will 
surpass that of the other, and glaciation ensue.'^ 

Such passing by one cap of the other in the race 
toward glaciation is bound to occur, whatever the eccen- 
tricity, if it be anything at all, provided the precipitation 
be sufficient. On the other hand, not only no glaci- 
ation can result unless the precipitation exceed a certain 
quantity, but in want of it the ice-cap is actually less 
in the hemisphere where we should expect it, that of 



extremes, than in the other. Whatever the cause of 
increased snowfall, the effect is the same. It is, then, 
the amount of precipitation, however it be brought 
about, and not increase of eccentricity, essential as 
eccentricity is, which is the determining cause of an 
ice age. 

To perish by wholesale glaciation is not therefore 
the inevitable doom of a planet. Unless water be in 
abundance, secular cooling will not necessarily bring it 
about, and Mars shows us 
that a planet may wholly 
escape such a termination 
to its career by having pre- 
viously parted with suffi- 
cient moisture, and actually 
enjoy an anti-glacial state 
in its old age. 

The thought leads us to 
the second matter in which 
the present state of Mars 
foretells the future of the 
earth. Not only does unhampered age ^^ preclude the 
possibility of a death by frost ; it tends to a death by 
thirst by deprivation of water. As we saw when 
reasoning upon the blue-green areas. Mars apparently 
had seas in the past, though it possesses none to-day. 
To the student of the planet the question at once 

Lines in the Dark Areas of 
Mars, showing that the 
Latter are not Seas. 

From a drawing made July 11, 1907. 


arises, how this not wholly regrettable deprivation was 
acquired, since it was not congenital. 

There are two ways in which a planet not only may, 
but inevitably must, be robbed of its water supply — 
from without and from within. It may lose its oceans 

November 5, 1907, September i, 1907. 

Paring on the Terminator (Right-hand Edge) of Mars where 
Dark Areas cross ; indicating that they lie at a Lower Level 
than the Rest of the Surface, and were once Seas. 

by absorption into its interior and by a slow depletion 
into space. While a body is yet molten, the conti- 
nuity of its substance bars entrance to aught else ; but 
as it cools and shrinks, fissures and crevices open in it, 
and into these the surface water sooner or later finds 
its way. As a planet ages, its very wrinkles must 
cause it to dry up. This is one drain upon its surface 
seas that is sure to occur. The other is equally sched- 
uled to happen. It depends upon the fact that gases 
are composed of particles called molecules travelling at 
great speeds. Temperature is the expression of 


this energy, varying, indeed, as the product of the 
square of the speed by the mass of the particle. Such 
motion it is that causes gases to expand. In their 
journeyings the molecules collide, and thus give and 
take velocity. In consequence, some are moving 
swiftly, some slowly. The molecules are flying about 
in all directions, and as long as they do not go too fast, 
the planet about which they act as atmosphere con- 
tinues to control them by its gravity. This it can 
continue to do up to a speed called its critical velocity, 
which is the velocity the planet can impart to a particle 
falling freely to it from infinite space. For the planet 
can annul just the speed it is able to cause and no 
more. But if, in their give and take of motion, a 
molecule gets to going faster than the critical velocity, 
it will escape into space and start on interstellar 
travels of its own. These molecules will never return 
to the body they have left, and as such desertion is 
constantly going on, it will eventually deplete the 
planet of all the gases it once possessed. 

Now, from any liquid surface evaporation is perpet- 
ually taking place ; so that an ocean is being slowly 
and silently lifted into the air. Ordinarily its particles 
fall again in the shape of rain, but not those which by 
collision gain sufficient speed. These from their tip- 
toe vantage-point take final flight into interplanetary 
space. The smaller the body, the sooner must it lose 


its seas, for the less can it hold on by its lesser gravity 
to its water-vapor. Three stages in the inevitable 
parting with its hydrosphere are exemplified to-day 
by the earth, Mars, and the moon. On the earth 
the sea-bottoms still hold seas, on Mars they only 
nourish vegetation, on the moon they contain noth- 
ing at all. 

Parity of reasoning points to the road the earth 
must follow. Sharpened by science, we actually per- 
ceive the progress along it that our world has already 
The oceans of Attention shows that loss of water has been going 
on through the eons that have passed, and that the 

appearing. D x ^ 

process is taking place under our very eyes to-day. 
Once laid down, the earth's oceans have been slowly 
disappearing since. The reason they have not wholly 
departed is partly because there was so much to go, 
partly because its greater mass has helped the earth to 
hold on to them the better. The speed of departure 
the earth can restrain is more than double that for 
Mars — 6.9 miles per second instead of 3.1 miles. 
Thus the way by the skies is less available. On the 
other hand, the greater initial heat of its interior has 
kept the water from sinking in to a degree beyond 
what is possible in a smaller globe. The earth has 
thus lagged in its losings, but it has lost, for all 



Withdrawal of water should show in a diminution Gain of land 

of the surface of the planet covered by the sea. Ob- ^ ""^ . 

i J America and 

servation proves this to be a fact. With research we Europe. 
may assure ourselves that the depletion is in process. 

From Dana's " Manual of Geology." (American Book Company.)] 

Map of North America, showing Approximately the Areas of Dry 
Land (indicated by the White Spaces) at the Close of Archaean 

The late Professor Dana of New Haven constructed 
maps of North America from the evidence afforded 
by the geologic sedimentary strata, showing what of it 
had been terra firma in the successive periods of 


geologic time. A comparison of his charts gives 
most interesting and conclusive proof that the land 
in North America has been gaining at the expense of 
the sea from the time the sea first was.* 

But North America was not alone in its natural 
territorial aggrandizement. Europe exemplifies the 
same generally steady, if temporarily fluctuating, con- 
quest of terrain. As in North America, the land 
started at the north, and encroached upon the ocean 
farther and farther southward. What we commonly 
regard as Europe was, in paleozoic times, under the 
surface of the sea. Only the north of Scotland and 
Scandinavia protruded. Had the present great navies 
of the world been in existence then, they would have 
found ample scope for their operations, but would 
have missed their present bases of supply, since they 
could have sailed over the sites of London, Paris, or 

Wherever geologists have studied them, the strata 
tell the same tale. The land has spread, the ocean 
shrunk from the time they first partitioned out the 
surface. Now, a general universal gain of the sort can 
mean only one of two things. Either the oceans have 
been deepening or disappearing. If crumplings of 
the crust have caused increased depression in the 
ocean basins, they should have been equally busied in 

* See "Mars and its Canals." Macmillan. 


elevating the continental plateaux. There is no evi- 
dence of any widespread raisings of the sort. For 
though mountain-chains have been pushed up, they 
are effects of local crumpling, not of broad buckler- 
like embossment. From the very fact that they are 
fractures, they relegate long, low uplifts to the past. 
We are left, then, with the alternative that the seas 
have been slowly reduced in volume. 

Testimony to this same effect keeps cropping up. Lowering of 
Only the other day the Chagos Archipelago, a little- 
known congeries of coral reefs south of the Maldives, 
was studied by Mr. Stanley Gardiner, of the Sladen 
Expedition, who concluded, from the appearance of 
the atolls, which, like oases in the desert, dot the 
waste of waters, that an alteration of level has been 
universal throughout the Indo-Pacific coral-reef re- 
gion, from latitude 30° N. to latitude 25° S. From 
the fact that it was so widespread, there being evi- 
dence of many local upheavals throughout the zone, 
he inferred it to be due to a withdrawal of water rather 
than to a change of level in the ocean floor. The 
amount required to account for the appearance varied 
from five to thirty-five feet. Thirty-five feet may at 
first sound small, but occurring over hundreds of 
thousands of square miles, it means a good deal of 
water lost. 

What is exhaling in the oceanic areas may be gauged inland seas. 


by what is transpiring in the smaller cut-ofF bodies 
of water, such as the Caspian, the Sea of Aral, 
and the Great Salt Lake. For the drainage basins of 
these inland seas are not only comparable with, but 
actually larger in proportion than, those of the oceans. 
Consequently they are fed the better of the two. 
Nevertheless, they are all with one consent evaporat- 
ing at a very perceptible rate. Most of them are 
below the level of the sea, which in itself speaks for 
the depletion undergone since they were left behind 
by the retreating main body of water. Marine shells, 
fishes, and seals, persisting in the Caspian still, testify 
to its abandoned character. Seals, indeed, witness to 
its now distancing its greater prototype in its haste 
to be gone, in spite of the huge fresh-water drainage 
it at present receives. For in the great Kara Bugas 
Gulf, on the Caspian's eastern side, the evaporation 
is so rapid that while a current sets into it from its 
narrow opening, with no compensating outward one, 
it is becoming so salt that seals can no longer live 
there. The Caspian is disappearing before our eyes, 
as the remains, some distance from its edge, of what 
once were ports mutely inform us.* Even so is it 
with the Great Salt Lake, the very rate of its sub- 
sidence being known and measured. 

The earth, then, is going the way of Mars. As 

*See Huntington, recent examination of the shores of the Caspian. 


there now, so here in time will be ushered in a phase Terrestriaiity 
of planetary evolution to which the earth as yet is rrueousness 
stranger — the purely terrestrial, as opposed to the 
present terraqueous, character of its surface. Much 
must surely follow such a change of scene. What 
it will be like we must study Mars to know, since 
Mars presents us the picture of a world that has 
reached that pass. To all of us this cannot but 
offer a certain exploratory incentive — one concerned 
not with space alone, but with time. For while we 
directly scan the planet for what it has to say about 
itself, we are indirectly reading a story which has some- 
thing to tell of our own future career. If we can 
succeed in separating in this the particular from the 
generic, what is local to Mars from what is cosmic in 
character, we shall do on a broad scale what the early 
astrologers thought to do on a narrow one, and in- 
stead of reading in the skies the fortunes of individuals, 
decipher there the fate of the whole earth. 

Something further of this sort we may indeed do, 
and this by help of the same principle that led us to 
the loss of seas. The drying up which causes their 
extinction is no less active on the land. Being a 
general deprivation common to the whole planet, the 
two kinds of surface must suffer synchronously. The 
effects, however, are much less bearable on terra firma. 
What in the withdrawal of water lowers oceans to 


affluence, reduces tracts of vegetation to penury. The 
once fertile fields become deserts. 
Deserts. Deserts already exist on the earth, and the name- 

less horror that attaches to the word in the thoughts 
of all who have had experience of them, or are gifted 
with imagination to conceive, is in truth greater than 
we commonly suppose. For the cosmic circumstance 
about them which is most terrible is not that deserts 
are, but that deserts have begun to be. Not as local,, 
evitable evils only are they to be pictured, but as the 
general unescapable death-grip on our world. They 
mark the beginning of the end. For these deserts are 
growing. First steps they are in the long retreat of 
water. What depauperates the forests to grass-lands,, 
and thence to wastes, must in turn attack the sea- 
bottoms when they shall have parted with their seas. 
Last of the fertile spots upon the planet because of the 
salts the streams have for ages washed down, and of 
the remnant of moisture that would still drain into 
them, eventually they must share the fortune of their 
predecessors, and the planet roll a parched orb through 
space. The picture is forbidding ; but the fact seems 
one to which we are constructively pledged and into 
which we are in some sort already adventured. 

Girdling the earth with what it takes but little 
personification to liken to the Hfe-extinguishing ser- 
pent's coils, run two desert-belts of country. The 


one follows, roughly speaking, the Tropic of Cancer, 
extending northward from it ; the other, the Tropic of 
Capricorn. Arizona is in the northern band, as are 
the Sahara, Arabia, and the deserts of central Asia. 

Now, these desert-belts are widening. In the great 
desert of northern Arizona the traveller, threading his 


Petrified Forest of Arizona. 

way across a sage-brush and cacti plain shut in by ab- 
rupt-sided shelves of land rising here and there some 
hundreds of feet higher, suddenly comes upon a 
petrified forest. Trunks of trees in all stages of 
fracture strew the ground over a space some miles 
in extent. So perfect are their forms, he is almost 
minded to think the usual wasteful wood-chopper has 
been by and left the scattered products of his art in 
littered confusion upon the scene of his exploit. Only 
their beautiful color conveys a sense of strangeness to 


the eye, and leaning down and touching them, he finds 
that they are — stone. Chalcedony, not carbon! 
Form has outlived substance and kept the resemblance, 
while the particles of the original matter have all been 
spirited away. Yet so perfect is the presentment, one 
can hardly believe the fact, and where one fallen giant 

Another View of the Petrified Forest of Arizona. 

The petrified 
forest of 

spans a barren canon, one almost thinks to hear the 
sound of water rushing down the creek. 

But it is some millions of years and more since this 
catastrophe befell, and the torrent, uprooting it, left it 
prone, with limbs outstretched in futile grasp upon 
the other side. A conifer it was, cousin only to such 
as grow to-day, and flourished probably in the Creta- 
ceous era ; for the land has not been under water here 
since the advent of Tertiary times. 


Nowhere near it, except for the rare cottonwoods 
along the bank of the Little Colorado, grows anything 
to-day. The land which once supported these forests is 
incompetent to do so now. Yet nothing has changed 
there since, except the decreasing water-supply. Dur- 
ing Tertiary and Quaternary time the rainfall has 
been growing less and less. Proof of this is offered 
by the great pine oasis that caps the plateau of which 
these petrified forests form a part, and is kernelled by 
the San Francisco peaks. The height above sea-level 
of the spot where the chalcedony trunks are strewn is 
about 4500 feet ; the lower present limit of the pine 
in its full development is 6500 feet. Two thousand 
feet upward the verdure-line has retreated since the 
former forests were. And this is no local alteration, 
for upon the other side of the plateau petrified remains 
of trees are similarly found. 

The line of perpetual green has risen because in 
desert regions the moisture is found most plentiful 
nearest to the clouds from which it falls upon a parch- 
ing earth. Streams, instead of gathering volume as 
they go, are largest near their source, and grow less 
and less with each fresh mile of flow. The brooks 
descending from the Anti-Lebanon, in Syria, water 
the gardens of Damascus, and, thence issuing upon 
the plain, lose themselves just beyond the threshold of 
its gates. So in the Arizona desert, though in a less 



degree ; and those who live there know it but too well. 
It is desert craft for Indians or cow-boys to seek water 
on the mesas, not at their base. To ascend after it is 
one of the footnotes of their trade. 
Egypt and The cvidcnce here brought before us of a secular 

parching of the land is not wholly confined to western 
North America. Crossing to the other side of the 
world, we come upon like remains. Upon the plateau 
above the Nile, near Cairo, the traveller goes to see 
another petrified graveyard of trees. It is prehistoric, 
yet contemporaneous with man ; for paleolithic and 
neolithic implements have been found not far away, 
showing that in the morning of his race man lived and 
hunted in these forests, where neither hunter nor 
hunted could exist to-day. 

Upon the southern coast of the Mediterranean, at 
the edges of the great Sahara, are to be seen to-day 
the ruins of vast aqueducts stalking silently across the 
plains. Fallen into decay now, they attest something 
more than the passing of the force of those who built 
them from the scene they once made great. Carthage 
has crumbled again to earth, and these sentinelling 
arches alone remain to show what tentacles of suste- 
nance it formerly thrust out. Still architecturally im- 
pressive, they span not space alone, but time. They 
testify to something to be carried as well as to a city 
to which to carry it. This, now, has disappeared 


as completely as its drinkers. At the present day the 
streams are incompetent to supply the aqueducts, the 
very presence of which attests that in the past this was 
not so. The land has parched since times so recent 
as to be historic, recorded by the monuments of man. 

Nor are we left to monuments for sole light upon 
the subject. The very fauna has changed. Animals 
that once inhabited the land are unable to live there 
now because of the increasing aridity of the habitat. 
Thus they add their testimony to that of the mute 
purveyors of water whose occupation is gone. The 
surprising thing is that it should all have happened so 
recently. In a startHng manner it brings before us the 
speed with which the desert is gaining on the habitable 

Palestine tells the same story. The land which Paiesrine. 
once flowed with milk and honey can hardly flow bad 
water now. Nor is this because the folk who made 
its greatness have since been scattered over the face of 
the earth. Much goes to ruin when the master hand 
is stilled, but no rich country ever lapsed to desert for 
this cause unless its fertility was irrigation-made. Con- 
clusive and convincing is here the evidence that the 
land itself has changed. 

Upon comparing the places where this desertism subtropical 
appears, it will be found that all occur in a band about ^^^1'°"^^^^^^ ^ 
the earth not far from either tropic, and extending 


north or south from it according to the hemisphere 
concerned. Now, when we turn to the tables of the 
rainfall for different parallels, we find this localization 

It is precisely in these belts that the average rainfall 
is least, except, indeed, far north, where the steppes 
attest to like aridity. The occurrence of the deserts 
is thus an affair of the circulation of the atmosphere, 
and from that fact is lifted at once into the region of 
general planetary evolution. For atmospheric circula- 
tion is a necessary consequence of a body having an 
atmosphere and being exposed to the action of the 
sun. The general effects of it are as follows : The 
equatorial region being the most continuously heated 
by the solar beams, the air above it rises and flows 
over at the top, necessarily poleward. The air about 
the tropics flows in to take its place. Meanwhile the 
lower portion of the equatorial emigrant, finding the 
space below less occupied, descends to earth in the 
forties, causing the prevailing winds in those regions. 
The upper part proceeds more or less spirally round 
the pole. This general circulation is independent in 
its main action of the character of the ground. Areas 
of sea and land modify the motions, but do not nega- 
tive the results. 

Now, keeping this circulation in the mind's eye, we 
note that, other things equal, those winds that descend 


from colder regions to warmer ones must be dry. 

For, on being heated, air becomes capable of taking ■ 

up more moisture than before, and is by this re- | 

strained from depositing the water it already contains i 
in the form of rain or snow or dew. It thus keeps 

with it such moisture as it has or as it acquires, and ' 
instead of being a bountiful dropper of fatness from 
its clouds, courses over the surface a scorching sirocco. 

Such is the fundamental, uncomplicated process, and, j 

in consequence, desert-belts are bound to form in time, i 

and just where we find those of the earth to-day, bar- i 

ring exceptions locally explained. For adventitious I 

bodies of water over which these winds pass may sup- i 

ply them with water which mountain-chains may pre- i 

cipitate again on their windward side by the cooling of j 

the winds due to rising up their flanks. Either of I 

these accidents of surface may thus modify the effect j 

without affecting the principle. I 

Turning now to Mars, we find what is but in its Planetary | 

infancy on earth, there in full control. Not only are *^/"^^ T ^ 

•' ■' ■' advanced on 1 

the desert-belts in existence, but the whole surface. Mars. 

except for the sea-bottoms, has gone the same way. j 

Five-eighths of it all is now an arid waste, unrelieved i 

from sterility by surface moisture or covering of cloud. ] 

Bare itself, it is pitilessly held up to a brazen sun, un- I 

protected by any shield of shade. \ 

That such is the case with our neighbor certain ; 


points about it indicate. The first of these is hue. 
The fiery color from which Mars was named turns out 
in the telescope to be an ochre dashed with red. This 
is just the tint our own deserts show when one looks 
down on them from a mountain peak. The next 
thing is their unalterableness. Except for seeming 
ruddier at times, they change not, the seasons that so 
transform the blue-green areas passing over them in 
vain. Thus both in look and deed they bespeak 
themselves vast Saharas, these great ochre stretches of 
the disk. 

Their positioning tells the same story. This we 
perceive on considering what their situation is as com- 
pared with what it should be for such state. 

Absence of moisture should not alter the general 
wind circulation sketched above, and we should expect 
to find, whatever the planet, the wet and dry zones 
much what they are on the earth, if trace of them still 
existed. To the map of Mars we therefore turn to 
mark whether this be so. In such envisagement, one 
antedating circumstance must be allowed for : the local 
positioning of the oceanic basins ; for an ocean, by 
reason of its original supply, would outlast its latitu- 
dinal time-limit. Its marine constitution would defy 
the law. 

Now, the oceans of Mars lay in the southern hemi- 
sphere of the planet. This qualifies the action in that 


hemisphere, and makes the southern subtropic zone 
one of verdure to-day. This, therefore, is no dis- 
proof of the general law ; it is but an added argument 
that these present blue-green areas were seas at some 
former epoch. 

Otherwise is it with the surfaceography of the 
northern hemisphere, since in the beginning that was 
probably fairly free from land-and-water distribution 
of a sufficiently pronounced type to hinder the play of 
the desert-making tendency. Here, then, we should 
look for confirmation of the principle that the sub- 
tropic zone should be more arid than the temperate 
one, and here we find something which is suggestive. 
The southern subtropic zone is destitute of blue-green 
areas — that is, areas of vegetation — all round the 
planet. Not so the temperate zone above it. In the 
latter are found all the larger blue-green regions in the 
planet's northern hemisphere — the Mare Acidalium, 
the Propontis, and the Wedge of Casius. And all 
these are approximately upon the same parallel of lati- 
tude. The Lucus Niliacus, and the Mare Acidalium 
stretch from latitude 29° N. to latitude ^^° ; the Pro- 
pontis from 37° to 48°; and the Wedge of Casius 
from ^^° to ^6°. That such consensus in situation can 
be due to chance is certainly unlikely. Here, then, 
linger the last vestiges of vegetation of the northern 


The opaline As important is the present great extent of the 
Martian deserts. Beautiful as the opaline tints of the 
planet look, down the far vista of the telescope-tube, 
they represent a really terrible reality. To the bodily 
eye, the aspect of the disk is lovely beyond compare ; 
but to the mind's eye, its import is horrible. That 
rose-ochre enchantment is but a mind mirage. A vast 
expanse of arid ground, world-wide in its extent, 
girdling the planet completely in circumference, and 
stretching in places almost from pole to pole, is what 
those opaline glamours signify. All deserts, seen from 
a safe distance, have something of this charm of tint. 
Their bare rock gives them color, from yellow marl 
through ruddy sandstone to blue slate. And color 
shows across space for the massing due to great extent. 
But this very color, unchanging in its hue, means the 
extinction of life. Pitilessly persistent, the opal here 
bears out its attributed sinister intent. 

To let one's thoughts dwell on these Martian Saharas 
is gradually to enter into the spirit of the spot, and so 
to gain comprehension of what the essence of Mars con- 
sists. Without such background always omnipresent 
in the picture, the lesser and more pregnant features fail 
of eiFect in their true value for want of setting off. To 
conceive of this great buckler of brazen sand and 
rock, level as a polished shield, and stretching to the 
far distance, to stand sharp-cut there by the horizon 


of a sky, unrelieved by so much as mountain-notching 
of its blue, is to realize in part what life on it must 
mean. Where days and months of travel would bring 
one no nearer to its edge, despair might well settle on 
the mind. And the sun in its daily course rises from 
out the stony waste only to set in it again. 

Pitiless indeed, yet to this condition the earth itself How the 
must come, if it last so long. With steady, if stealthy, j^J^'^^a!! ^''^' 
stride, Saharas, as we have seen, are even now possess- 
ing themselves of its surface. The outcome is doubt- 
less yet far off, but it is as fatalistically sure as that to- 
morrow's sun will rise, unless some other catastrophe 
anticipate the end. It is perhaps not pleasing to learn 
the manner of our death. But science is concerned 
only with the fact, and Mars we have to thank for its 

Before the final stage in the long life drama of a 
planet is thus brought to its close, there will come 
a time when the water, having left the surface, still 
lingers for a little in the air. For the atmosphere is 
the pathway the water takes to the sky. Insufficient 
in amount to leave a surplus on the ground in the 
shape of oceans, or even lakes and ponds, a certain 
quantity will still hover up above. From the mode 
of its withdrawal, a planet must lose its surface water 
long before it loses the aqueous vapor from its air, so 
that the absence of the one argues nothing against the 


presence of the other. Now there are physical reasons 
connected with evaporation which would make for 
more water in the air of Mars than of the earth, and 
yet not permit of precipitation. 

In Chapter III we marshalled the evidence we have 
that water exists on the surface of Mars : in the polar 
caps and practically nowhere else. We have now to 
see what proof there is that it still exists in the Martian 
air. The evidence on which this rests is twofold: the 

Effect of the Spring Mist around the North Polar Cap of Mars 
Drawn January 25, 1905 (Martian date, June 23). 

first telescopic, in the aspect of the disk. Water- vapor, 

as such, of course, we could not expect to see, as it is 

invisible constitutionally. But when, suspended in the 

air, it condenses into drops or spicules, we might hope 

for detection. Such proves a possibility occasionally 

on Mars. 

Water present As the North polar Cap melts, there comes a season 

in the Mar- ^}^gj^ ^^ indefinite pearly appearance fringes its edge, 

phere. obliterating its contours, which before were sharp. 

This persists for some weeks, off and on, and when at 


last it clears, the cap is seen to be reduced to its least 
extent. That it is mist caused by the melting of the 
cap there is little doubt. 

But there is another instrument of astronomical re- 
search the special field of which is the study of the 
invisible. To see indirectly what cannot be seen direct 
is the province of the spectroscope. The spectroscope 
consists of a prism or train of prisms which disperse 
white light into a rainbow-tinted ribbon known as the 
spectrum, made up of rays of different wave-length from 
violet at one end to red at the other. Now it is a 
property of a gas, through which light passes, to absorb 
certain of the rays peculiar to itself, and so form dark 
lines across the spectrum at those points. Most of 
the lines thus observed in the solar spectrum come 
from gases in the photosphere of the sun, but there 
are certain others which arise in our own atmospheric 
envelope and are called telluric lines in consequence. 
Such are the oxygen and water-vapor bands. If now 
another planet, such as Mars, possessed either of these 
gases in its atmosphere, the light reflected from it 
should disclose the fact by deepening these bands. 
Much was hoped from the spectroscope on this 

Up to and beyond the time when the lectures were 
written, of which this book is the outcome, the spec- 
troscope had not proved itself a sufliciently delicate in- 


strument to give other than an uncertain answer on the 
presence or absence of water-vapor on Mars. Huggins^ 
Vogel, Janssen, all thought to see evidence of it there ; 
Campbell, with more accurate instruments, could find 
none. Nor could any be obtained under still more 
favorable conditions of air and instrument at Flagstaff. 
The reason for inconclusion, though unsuspected at the 
time, lay in the position of the bands in the spectrum 
produced by water-vapor. These begin, indeed, in the 
yellow, are present in the orange and light red, but are 
broadest and darkest in the partially visible deep 
red and in the invisible spectrum beyond it. These 
strongest bands were beyond the appliances of the day 
for purposes of careful comparison, while the others 
were not sufficiently salient to make delicate contrasts 

In the spring of 1908, Mr. V. M. Slipher succeeded 
at Flagstaff in bathing plates to sensitiveness through 
the red, and, exposing these plates in the camera of the 
spectroscope, photographed the spectrum first of Mars 
and then of the moon at the same altitude to well 
beyond the point where the great water-vapor band 
known as "a" lies. He took in all eight such plates, 
with the result that the " a " band showed stronger in 
the spectrum of the planet than in that of the moon. 
Now in the case of the moon it is through our own 
atmosphere only that we are looking ; in the case of 

























• <; 








^ c 















»> Water-vaj>07- 


Mars, through our own plus that of Mars. Any dif- 
ference between the two must be due to the Martian 
air. A strengthening, then, in the expression of the 
"a'* bands denoted water-vapor present in the atmos- 
phere of Mars. Here we have the much-desired 
spectroscopic proof, and with it the explanation of why 
so much uncertainty existed among eminent spectro- 
scopists before. To those versed in Mars it is chiefly 
of the nature of corroboration. For to the mind's eye 
reasoning had already revealed that water-vapor must 
be there, but now the bodily eye of any one may see. 
The thing is curiously paralleled by the way in which 
Clerk Maxwell's analysis showed the rings of Saturn 
to be made of discrete particles before the spectroscope 
in Keeler's ingenious hands stamped its evidence on a 
photographic plate. 

That water-vapor exists in the air is cause for its 
deposition on the ground. But to be precipitated and 
to stay so are two very different things. The only 
way in which so scant an amount could remain de- 
posited in any part of the planet would be as frozen 
moisture about the pole. For as snow it stays 
fixed, evaporation at a low temperature going so 
much less fast than from water under its appropriate 
higher one. A snow-field suitably situated might thus 
persist while a pond would speedily disappear. The 
polar snows would be the only place where moisture 


could descend to the surface to stay, being brought to 
the polar regions by the planetary winds. 

With regard to the distribution of the humidity, 
what scant moisture the desert-born equatorial winds 
might possess would be deposited northward as they 
cooled, in part impermanently in the forties, in part 
more permanently at the poles. The return flow of 
air in winter, being steadily warmed, would not tend to 
deposit moisture down the disk ; nor in summer either, 
to any extent, although from the melting of the cap 
such winds would then be more charged with vapor. 
Unlike our own earth, therefore, moisture would pro- 
ceed poleward, to remain there. Not only, therefore, 
is the water much less in amount on Mars, but what 
is there tends to be kept about the poles. The only 
available supply lies in the arctic and antarctic regions, 
stationary on the ground or else is in process of jour- 
neying round to it again. 

In this last stage of temporizing, the water that 
once as such bespread Mars's face now is. The well- 
nigh total disappearance of the one cap, and the entire 
extinction of the other, show how each summer melts 
what the winter had deposited, and that in both cases 
this is nearly the sum total of the cap. Covering as 
each does so much territory, one might suppose the 
water not scanty, but comparable in quantity to the 
earth's supply. If we calculate it, however, we shall 


find this anything but the case. At Point Barrow, in 
Alaska, in latitude 71° N., where the temperature is be- 
low freezing from September i to June 15, 75 inches 
of snow fall during the nine and a half months. 
Ten inches of snow are equal to one inch of water. 
This quantity, then, measures the amount of the 
Earth's impermanent cap, and forms a basis for com- 
parison with the depth of the snow-cap melted on 
Mars. It seems, too, not an improbable value for 
what occurs there ; for though on the one hand it is 
likely that day by day the snowfall is greater at Point 
Barrow than on Thyle, in Mars, at the same latitude, 
on the other, the winter season is there twice as long. 
To be lavish, we may estimate that the equivalent of 
100 inches of snow fall on Thyle. That would mean 
10 inches of water. Now, the southern cap of Mars, 
the larger of the two, covers 96° across at its 
greatest, which makes its area equal to one-fifth of the 
whole surface of the planet. To this we need not add 
the other cap, since it at the time stretches over only 
6°, a vanishing quantity in comparison. On earth, 
oceans cover 72 per cent of the surface, and are, on 
the average, 2100 fathoms deep. Calculation from 
these data gives the amount of water on the earth as 
189,000 times that on Mars. We said rightly, then, 
that Mars was badly off for water. 

In consequence of this state of things, the water- 


supply of the planet is both scant in amount and teth- 
ered at that. For it is tied up during the greater part 
of the year at one pole or the other. For a few weeks 
only of each six months it stands unlocked, first in 
the arctic, then in the antarctic, zone. Then, and then 
only, may this deposit, meagre as it is, be drawn upon. 
Mars is indebted for the staff of life to a polar pittance 
sparsely doled out, and that only at appointed times. 
The surface Study of the natural features of the planet leaves us, 

waterless then, this picture of its present state — a world-wide 
world. desert where fertile spots are the exception, not the 

rule, and where water everywhere is scarce. So scanty 
is this organic essential, that over the greater part of 
the surface there is none to quicken vegetation or to 
support life. Only here and there by nature are pos- 
sible those processes which make our earth the habit- 
able, homehke place we know. In our survey of 
Mars, then, we behold the saddening picture of a 
world athirst, where, as in our own Saharas, water is 
the one thing needful, and yet where by nature it can- 
not be got. But one line of salvation is open to it, 
and that lies in the periodic unlocking of the remnant 
of water that each year gathers as snow and ice about 
its poles. 
A high type The evidence of observation thus bears out what 
of life probable ^^ might susDCCt from the planet's smaller size : that 

on Mars. . . . . 

it is much farther along in its planetary career than is 


our earth. This aging in its own condition must have 
its effect upon any life it may previously have brought 
forth. That life at the present moment would be 
likely to be of a high order. For whatever its actual 
age, any life now existent on Mars must be in the land 
stage of its development, on the whole a much higher 
one than the marine. But, more than this, it should 
probably have gone much farther if it exist at all, for 
in its evolving of terra firma. Mars has far outstripped 
the earth. Mars's surface is now all land. Its forms 
of life must be not only terrestrial as against aquatic, 
but even as opposed to terraqueous ones. They must 
have reached not simply the stage of land-dwelling, 
where the possibilities are greater for those able to em- 
brace them, but that further point of pinching poverty 
where brain is needed to survive at all. 

The struggle for existence in their planet's decrepi- 
tude and decay would tend to evolve intelligence to 
cope with circumstances growing momentarily more 
and more adverse. But, furthermore, the solidarity 
that the conditions prescribed would conduce to a 
breadth of understanding sufficient to utilize it. Inter- 
communication over the whole globe is made not only 
possible, but obligatory. This would lead to the 
easier spreading over it of some dominant creature, — 
especially were this being of an advanced order of in- 
tellect, — able to rise above its bodily limitations to 


amelioration of the conditions through exercise of 
mind. What absence of seas would thus entail, 
absence of mountains would further. These two ob- 
stacles to distribution removed, life there would tend 
the quicker to reach a highly organized stage. Thus 
Martian conditions themselves make for intelligence. 
The probabii- Our knowledge of it would likewise have its likeli- 
Marsatthe" ^^^^ increascd. Not only could any beings there dis- 
present time, closc their prescncc only through their works, but 
from the physical features the planet presents, we are 
led to believe that such disclosure would be distinctly 
more probable than in the case of the earth. Any 
markings made by mind should there be more defi- 
nite, more uniform, and more widespread than those 
human ones with which we are familiar. More domi- 
nant of its domicile, it should so have impressed itself 
upon its habitat as to impress us across intervening 

What the character of such markings might be, we 
shall best conceive by letting the pitiless forbiddingness 
of the Martian surface take hold upon our thought. 
Between the two polar husbandings of the only water 
left, stands the pathless desert — pathless even to the 
water semiannually set free. Only overhead does the 
moisture find natural passage to its winter sojourn at 
the other pole. Untraversable without water to 
organic life, and uninhabitable, the Sahara cuts off 


completely the planet's hemispheres from each other, 
barring surface commerce by sundering its supplies. 
Thirst — the thirst of the desert — comes to us as we 
realize the situation, parching our throat as we think 
of a thirst impossible of quenching except in the far- 
ofFand by nature unattainable polar snows. 

Turning again to Mars with quickened sense, we 
witness an astounding thing, the study of which in its 
mien, its moods, and its meaning, the next two chap- 
ters will take up. 

and the canals. 



THIRTY years ago what were taken for the con- 
tinents of Mars seemed, as one would expect 
continents seen at such a distance to appear, virtually- 
Schiapareiii In 1 877, howcvcr, a remarkable observer made a 

still more remarkable discovery ; for in that year 
Schiapareiii, in scanning these continents, chanced 
upon long, narrow markings in them which have 
since become famous as the canals of Mars. Sur- 
prising as they seemed when first imperfectly made 
out, they have grown only more wonderful with 
study. It is certainly no exaggeration to say that 
they are the most astounding objects to be viewed in 
the heavens. There are celestial sights more dazzling,, 
spectacles that inspire more awe, but to the thoughtful 
observer who is privileged to see them well there is. 
nothing in the sky so profoundly impressive as these 
canals of Mars. Fine lines and little gossamer fila- 
ments only, cobwebbing the face of the Martian disk,, 
but threads to draw one's mind after them across the 
millions of miles of intervening void. 

Although to the observer practised in their detec- 
tion they are at certain times not only perfectly dis- 



tlnct, but are not even difficult objects, — being by no 
means at the limit of vision, as is often stated from 
ignorance, — to one not used to the subject, and 
observing under the average conditions of our trouble- 
some air, they are not at first so easy to descry. Had 
they been so very facile, they had not escaped detec- 
tion so long, nor needed Schiaparelli, the best observer 
of his day, to discover them. But in good air they 
stand out at times with startling abruptness. I say 
this after having had twelve years' experience in the 
subject — almost entitling one to an opinion equal to 
that of critics who have had none at all. 

How beside the mark it is to credit them to illusion 
may at once be appreciated from the fact that experi- 
ment shows the main ones to appear through the tele- 
scope of the same size as a telegraph wire seen with the 
naked eye at a distance of a hundred and fifty feet. 
But if the air be not steady, they are blurred almost 
out of recognition. 

With our air at its best, the first thing to strike one 
in these strange phenomena is their geometric look. 
It has impressed every observer who has seen them 
well. It would be hard to determine to which of 
their peculiar characteristics this effect was specially 
due. Indeed, it is probably attributable to their com- 
bination ; for distinctive as each trait is alone, their 
summation is multiplicitly telling. That the lines run 



quite straight from point to point — that is, on arcs of 
great circles, or else curve in an equally determinate 
manner; that they are of uniform width throughout; 
that their tenuity is extreme and that they are of 
enormous length, are attributes each of which is geo- 
metrically startling and which, taken together, enhance 
this in geometric ratio. 
Lines are That the Hncs are absolutely straight — which 

means that on a sphere like Mars they follow arcs 
of great circles — is shown by two facts which fay 
into one another. One of these is that they look 
straight to the observer when central enough not to 
have foreshortening tell. This could not happen 
unless they were the shortest possible lines between 
their termini. The other proof consists in their fitting 
together to form a self-agreeing whole when the result 
of all the drawings — hundreds in number at each 
opposition — are plotted on a globe. 

In regard to their width, it would be nearest the 
mark to say that they had none at all. For they 
have been found narrower and narrower as the con- 
ditions of scanning have improved. By careful ex- 
periments at Flagstaff it has been shown that the 
smallest appear as they should were they but a mile 
across. The reason so slender a filament is visible is 
due to its length, and this probably because of the 
number of retinal cones that are struck. Were only 

HvDE Park and Park Lane, London, k 
From a Free Balloon. 

From Photographs at 2200 feet by Profs. Rotch and Lowell 

Hyde Park and The Serpentine 
Showing Artificial Markings of Earth seen from Space. 


one affected, as would be the case were the object a 
point, it certainly could not be detected.^^ 

So much for the smallest canal now visible with our 
present means. The larger are much more conspicu- 
ous. These look not like gossamers, as the little 
ones do, but like strong pencil-lines. Comparison 
with the thread of the micrometer gives for the average 
canal a breadth of about ten miles. The canals, how- 
ever, are by no means of a uniform width. Indeed, 
they are of all sizes, from lines it would seem impos- 
sible to miss to others it taxes attention to descry. 

All the more surprising for their relative diversity 
is the remarkably uniform size of each throughout its 
course. So far as it is possible to make out, there is 
no perceptible difference in width of a canal, when fully 
developed, from one end of it to the other. Certainly 
it takes a well-ruled line on paper to look its peer for 
regularity and deportment. 

True thus to itself, each canal differs from its neigh- 
bor not only in width, but in extension. For the 
canals are of very various length. Some are not above 
250 miles long, while others stretch 2500 miles from 
end to end. Nor is this span by any means the limit. 
The Eumenides-Orcus runs 3450 miles from where it 
leaves the Phoenix Lake to where it enters the Trivium 
Charontis. Enormous as these distances are for lines 
which remain straight throughout, they become the 



more surprising when we consider the size of the 
planet on which they are found. For Mars is only 
4220 miles through, while the earth is 7919. So that 

/ --* 

A Section of the Canal Eumenides-Orcus terminating in the 
Junction Trivium Charontis 
The length of this canal is 3500 miles. The remainder of the canal may be seen 
on the hemisphere shown on p. 156, where it starts from Phoenix Lake (Lucus 

a canal 3450 miles long, for all its unswervingness 
to right or left, actually curves in its own plane 
through an arc of some 90*^ round the planet. 
It is much as if a straight line joined London to 
Denver, or Boston to Bering Strait. 


It should be remembered, however, that it is the 
actual, not the relative, length we have really to 
consider. But this is surprising enough — more than 
sufficient in the Eumenides-Orcus to span the 
United States. 

Odd as is the look of the individual canal, it is 
nothing to the impression forced upon the observer 
by their number and still more by their articulation. 
When Schiaparelli finished his life-work, he had de- 
tected 113 canals; this figure has now been increased 
to 437 by those since added at Flagstaflf. As with 
the discovery of the asteroids, the later found are as 
a rule smaller and in consequence less evident than 
the earlier. But not always ; and, unlike asteroid 
hunting, it is not because of easy missing in the vast 
field of sky. The cause is intrinsic to the canal. 

This great number of lines forms an articulate 
whole. Each stands jointed to the next (to the 
many next, in fact) in the most direct and simple 
manner — that of meeting at their ends. But as 
each has its own peculiar length and its special 
direction, the result is a sort of irregular regularity. 
It resembles lace-tracery of an elaborate and elegant 
pattern, woven as a whole over the disk, veiling the 
planet's face. By this means the surface of the 
planet is divided into a great number of polygons, 
the areolas of Mars. 


Schiaparelli detected the existence of the canals 
when engaged in a triangulation of the planet's sur- 
face for topographic purpose. What he found was 
a triangulation already made. In his own words, 
the thing " looked to have been laid down by rule 
and compass.'* Indeed, no lines could be more pre- 
cisely drawn, or more meticulously adjusted. Not 
only do none of them break off in mid-career,* to 
vanish, as rivers in the desert, in the great void of 
ochre ground, but they contrive always in a most 
gregarious way to rendezvous at special points, run- 
ning into the junctions with the space punctuality 
of a train on time. Nor do one or two only man- 
age this precision ; all without exception converge 
from far points accurately upon their centres. The 
meetings are as definite and direct as is possible to 
conceive. None of the large ochre areas escapes 
some filament of the mesh. No single secluded spot 
upon them could be found, were one inclined to 
desert isolation, distant more than three hundred 
miles from some great thoroughfare. 
Canals in For many years — in fact, throughout the period 

of observation of the great Italian — the canals were 
supposed to be confined to the bright or reddish 
ochre regions of the disk. None had been seen by 

* Their seeming occasionally to do so is due to their mode of growth seasonally 
or to certain latitudes being better shown than others at the time. 

dark regions. 


him elsewhere, and none was divined to exist. But 
in 1892, W. H. Pickering, at Arequipa, saw Hnes 
in the dark regions; and, in 1894, Douglass, at Flag- 
staff, definitely detected the presence of a system of 
canals criss-crossing the 
blue-green similar to that 
networking the ochre. 
Later work at Flagstaff 
has shown all the dark 
areas to be thus seamed 
with lines, and lastly has 
brought out with emphasis 
the pregnant fact that 
these are continued by 
others connecting with the 

polar snows.* Thus the system is planet-wide in 
its application, while it ends by running up to the 
confines of the polar cap. The first gives it a 
generality that opened up new conceptions of its 
office, the second vouchsafes a hint as to its origin. 
For many years the pioneers in this discovery of 
another world had their revelations strictly to them- 
selves, decried as baseless views and visions by the 
telescopically blind. So easily are men the dupes of 

Canals in Dark Regions con- 
necting WITH THE Polar Cap 

* Previous to 1907 the fact was known only for the northern hemisphere. In 
1907 the Flagstaff observations disclosed the important extension of the scheme 
through the antarctic zone 5 a striking confirmation of theory. 


their own prejudice. But in 1901 attempts began to 
be made at Flagstaff to make them tell their own 
story to the world, writing it by self-registration on 

a photographic 
plate. It was 
long before 
they could be 
compelled tc 
do so. The 
first attempts 
showed noth- 
ing; the next, 
two years later, 
did better, 
evoking faint 
forms to the 
initiate, but to 
them alone; but 
two years later 
still, success 

Photographic Apparatus of the Lowell 


Devised by Mr. C. O. Lampland, and used in getting 

the photographs of the canals of Mars. 

crowned the 
long endeavor. At last these strange geometricisms 
have stood successfully for their pictures. The photo- 
graphic feat of making them keep still sufficiently 
long — or, what with heavenly objects is as near as 
man may come to his practice with human subjects, 
the catching of the air-waves still long enough to 


secure impression of them upon a photographic plate 
— has been accomplished by Mr. Lampland. After 
great study, patience, and skill he has succeeded in 
this remarkable performance, of which Schiaparelli 
wrote in wonder to the present writer : " I should 
never have believed it possible." 

Regard for positioning is one of the most signifi- 
cant characteristics of the lines. They join all the 
salient points of the surface to one another. If we 
take a map of the planet and connect its prominent 
landmarks by straight lines, we shall find, to our 
surprise, that we have counterfeited the reality. That 
they are so regardant of topography on the one hand, 
and so regardless of terrain on the other, gives a 
most telltale insight into their character ; it shows 
that they are of later origin than the main markings 
themselves. For they bear testimony to this without 
regard to what they are. Their characteristics and 
their attitudes, in short, betray that at some time 
subsequent to the fashioning of the planet's general 
features the lines were superposed upon them. 

But this is not all. Since the seas probably were canais super- 
seas in function as in name once upon a time, the ^°l^ T^^ 

r ^ main features, 

superposition must have occurred after they ceased 
to be such ; for clearly the lines could not have been 
writ on water, and yet be read to-day. We are 
thus not only furnished with a datum about the 


origin of the canals, but with a date determining 
when it took place. The date marks a late era in 
the planet's development, one subsequent to any the 

Hemisphere showing the Oasis called Ascraeus Lucus 

From this radiate many canals. Also in the upper right-hand space is shown the 
continuation of the Eumenides-Orcus. 

earth has yet reached. This accounts for the diffi- 
culty found in understanding them, for as yet we 
have nothing like them here. 
Oases. Next in interest to the canals come the oases. 


Many years after the detection of the canals, scrutiny 
revealed another class of detail upon the planet of 
an equally surprising order. This was the presence 
there of small, round, dark spots dotted over the 
surface of the disk. Seen in any number, first by 
W. H. Pickering in 1892, they lay at the meeting-- 
places of the canals. He called them lakes. Some 
few had been caught earlier, but were not well 
recognized. We now know 186 of them, and we 
are very certain they are not lakes. In the case of 
one of them, the Ascraeus Lucus, no less than sev- 
enteen canals converge to it. 

It thus appears that the spots make, as it were, the 
knots of the canal network. They emphasize the 
junctions in look and at the same time indicate their 
importance in the system. For just as no spot but 
stands at a junction, so, reversely, few prominent junc- 
tions are without a spot, and the better the surface is 
seen, the more of these junctions prove to be provided 
with them. 

Their form is equally demonstrative of their func- 
tion. They are apparently self-contained and self- 
centred, being small, dark, and, as near as can be 
made out, round. It is certain that they are not 
mere reenforcements of the canals due to cross- 
ing, for crossings do occur where none are seen, 
while the lines themselves are perfectly visible, and 


of the same strength at the crossing as before and 

We now come to a yet more surprising detail. 
The existence of the single canals had scarcely been 
launched upon a world quite unprepared for their 
reception, and duly distant in their welcome in con- 
sequence, before that world was asked to admit some- 
thing more astounding still ; namely, that at certain 
times some of these canals appeared mysteriously 
paired, the second line being an exact replica of the 
first, running by its side the whole of its course, how- 
ever long this might be, and keeping equidistant from 
it throughout. The two looked like the twin rails- 
of a railway track. (See map opposite page 217.) 

To begin by giving an idea of the phenomenon, I 
will select a typical example, which happened also tO' 
be one of the very first observed by me — that of the 
great Phison. The Phison is a canal that runs for 2250 
miles between two important points upon the planet's 
surface, the Portus Sigaeus, halfway along the Mare 
Icarium, and the Pseboas Lucus, just off the Proto- 
nilus. In this long journey it traverses some six 
degrees of the southern hemisphere and about forty 
degrees of the northern. In 1894 the canal was first 
seen as a single, well-defined line — not a line that 
admitted of haziness or doubt, but which was as 
strictly self-contained and slenderly distinguished as 


any other single canal on the planet. A Martian 
month or more after it thus expressed itself, it 
suddenly stood forth an equally self-confessed double, 
two parallel lines replacing the solitary line of some 
months before. Not the slightest difference in the 
character, direction, or end served was to be detected 
between the two constituents. Just as certainly as a 
single line had shown before, a double line now showed 
in its stead. 

Study of the doubles has been prosecuted for some 
years now at Flagstaff, and its prosecution has gradu- 
ally revealed more and more of their peculiarities. 
The first thing this study of the subject has brought 
out is that duality, bilateralism, is not a universal 
feature of the Martian canals. Quite the contrary. 
It cannot be said in any sense to be even a general 
attribute of them. The great majority of the canals 
never show double at any time, being persistently and 
perpetually single. Out of the 437 canals so far dis- 
covered, only 51 have ever shown duplicity. From 
this we perceive that less than one-eighth of all the 
canals visible affect the characteristic, nor are these 51 
distinguished in any manner, by size or position, from 
those of the other 386 that remain pertinaciously 
single. They are neither larger nor smaller, longer 
nor shorter, nor anything else which would suffice on 
a superficial showing to distinguish their strange in- 


Width differs 
for different 

herent potentiality from that of those which do not 

possess the property. 

Now, this fact directly contradicts every optical 

theory of their formation. If the doubles were prod- 
ucts of any optical law, that 
law should apply to all canals 
alike, except so far as posi- 
tion, real or relative upon 
the disk, might affect their 
visibility. Now, the double 
canals are not distinguished 
in any of these ways from 
their single sisters. They 
run equally at all sorts of 

angles to the meridian, and are presented equally at 

all sorts of tilts to the observer ; and yet the one kind 

keeps to its singularity, and the other to its preference 

for the paired 


The next point 

is that the width 

of the gemination 

— the distance, 

that is, between 

the constituents 

_ . . A Mass of Double Canals, Elysium (see 

or the pair is the Hemisphere, Page 150) 

not the same for From a drawing made on June i, 1903. 

Single and Double Canals 
In a drawing made July 15, 1905. 


all the doubles. Indeed, it varies enormously. Thus, 
we have at one end of the list the little, narrow Djihoun, 
the constituents of which are not separated by more 
than two degrees ; while at the other end stands the 
Nilokeras, with its members eleven degrees apart. 
That is, we have a parallelism of seventy-five miles in 
one case, and one of four hundred in another. This 
fact disposes again of any optical or illusory production 
of the lines ; for were their origin such, they would all 
be of the same width. 

Position is the next thing to be considered. A 
general investigation of this shows some results which 

are highly in- _._ __ ______^ 

structive. To 

begin with, the ^^ ^ ">^ 

distribution of ^-^s..^ f .cC- ' '^"'^ 


the doubles may ^-•- ^ ^^^ .. .^^ 
be broadly 

looked at from -^^^^^r ^/"iC-^,,,;>^> 

two points of ^^Aif^',^ 

view, that or a Mass of Single Canals about Lucus 

their longitudi- Phoenicis (see the Hemisphere, Page 156) 

, , . T I From a drawing made in November, 1894. 

nal or latitudmai 

placing upon the planet. Considering the longitudinal 
first, if we cut the planet in halves, the one hemi- 
sphere extending from longitude 20° to 200° and 
the other from 200° to 20°, more than two-thirds of 


all the double canals turn out to lie in the second 
section ; the numbers being fifteen in the one to 
thirty-six in the other. It appears, then, that the 
doubles are not evenly distributed around the 

We now turn to their partition according to latitude, 
and here we are made aware of a significant distribu- 
tion affecting them. If we divide the surface into 
zones of ten degrees each, starting from the equator 
and travelling in either direction to the pole, and 
count the double canals occurring in each, we note a 
marked falling off in their number after we leave the 
tropic and subtemperate zones, and a complete cessa- 
tion of them at latitude 6^° north. The actual num- 
bers are as follows : — 

Between 90° S. and 30° S. . . . . o 

Between 30° S. and 20° S 3 

Between 20° S. and 10° S 9 

Between 10° S. and 0° ..... 20 

Between 0° and 10° N 29 

Between 10° N. and 20° N 26 

Between 20° N. and 30° N 23 

Between 30° N. and 40° N 20 

Between 40° N. and 50° N 4 

Between 50° N. and 60° N 3 

Between 60° N. and 63° N 2 

Between 63° N. and 90° N. . . . . o 


As a double may pass through more than one zone, it 
may be counted more than once, which explains the total 
in the table, though the doubles number but fifty-one. 

Thus the doubles are tropical features of the planet. Area of zones. 
not general ones. Decidedly this proclaims again 
their reality, for were they optical only, they could not 
show such respect for the equator — a respect worthy 
of commendation from Sydney Smith. 

Another of their peculiarities consists in their being 
confined to the light regions. For, with one possible 
exception, no doubles have been detected in the dark 
areas of the disk, whereas plenty of single canals have 
been found there. 

Yet to the dark areas they stand somehow beholden. 
For the great majority of them debouch from what were 
once thought seas, to traverse the great deserts. Of the 
51 doubles, no fewer than 28 are thus immediately con- 
nected with the 'seas.' But this is not the end of the 
dependence. F'or the remaining canals, 23 in number, 
each connect with one or other of the doubles that per- 
sonally connect with these dark regions. In all but two 
cases the secondary dependence is direct ; in these two 
a smaller dark patch occurs in the line of the connection. 

Thus, the double canals show a most curious sys- 
tematic dependence upon the great dark areas of the 
southern hemisphere. In this they reproduce again the 
general dependability of single canals upon topographic 


features ; but with more emphatic particularity, for they 
prove that not only are prominent points for much 
in their localization, but that different kinds of terrain 
are curiously concerned. The relation of one kind of 
terrain to another is essential to their existence, since 
they are virtually not found in the blue-green areas, and 
yet are found in the light only in connection with the 
blue-green. That the blue-green is vegetation and the 
ochre desert leads one's thought to conjecture beyond. 
To turn, now, to another mode of position, we 
will look into the direction in which these doubles run. 
To do this, we shall segregate them according to the 
compass-points. Any one of them, of course, runs 
two ways ; as, for example, N.N.E. and S.S.W., and 
we shall therefore have but half the whole number of 
compass-points to consider. Taking the direction 
two points apart, we shall have eight sets, dividing 
the canals into bunches, as follows : — 

S. and N 7 

S.S.E. and N.N.W 5 

S.E. and N.W . 4 

E.S.E. and W.N.W. ...... 3 

E. and W 6 

E.N.E. and W.S.W 6 

N.E. and S.W 12 

N.N.E. and S.S.W. ....... 8 



At first, to one considering this table, no marked 
preponderance for one direction over another mani- 
fests itself in the orientation. Still, a certain trend to 
the east of north as opposed to the west of north is 
discernible. For 25 doubles run within 45° of north- 
east and southwest, to 12 only that do the same thing 
for northwest and southeast. Following up the hint 
thus given us, we proceed to apportion the canals first 
into quadrantal points. The result is a fairly equable 
division all around the circle. Now, as a matter of 
fact, by lumping the doubles of the two hemispheres 
together, we have almost obliterated a striking fact 
which lies hidden in the table. If, instead of thus com- 
bining them, we separate those exclusively of the north- 
ern hemisphere from those of the southern one only, 
and now note in each of these what proportion trend to 
the west of south as against those that run to the east 
of it, and vice versa^ we come out with significant re- 
sults. In the northern hemisphere, the proportion of 
double canals to show a westward trend as opposed 
to an eastern is 17 to 4. In the southern hemisphere, 
the easterly-trending outnumber the westerly-trending 
by I to o ; while for those whose course is common 
to both hemispheres we find for the ratio of south- 
western to southeastern 8 to 7. 

How can this be explained ? Consider a particle 
descending from the pole to the equator under the 


push of a certain momentum. As the particle (of 
water, for example) reaches a lower and lower latitude, 
it comes upon a surface which is travelling faster and 
faster eastward, because, since all parts of the body, 
whether the earth or Mars, rotate in the same time, 
those particles where the girth is greatest have the 
farthest distance to go. 

In consequence of this the particle would con- 
stantly be going at a less speed to the east than 
the spot upon which it found itself adventured, and 
so relatively to that place would move to the west. 
From the south pole to the equator, therefore, its 
course would always show a deviation southwesterly 
from a due north and south direction. 

In the southern hemisphere, on the other hand, 
since the rotation of the planet is the same, its direc- 
tion with regard to the pole is different, for the sur- 
face upon which the particle successively comes still 
sweeps to the east. It would, therefore, relatively 
to the surface, move to the northwest, and we 
should have in this hemisphere a northwesterly trend 
from the pole equatorward. 

This is actually what we see in the doubles of 
Mars. The proportion of canals trending to the 
west as against those trending to the east in the 
northern hemisphere is, as we have seen, 17 to 4 ; 
while in the southern hemisphere the proportion 


trending to the east Is i to o. As for canals occupy- 
ing both grounds a compromise is effected, the canals 
running according to the hemisphere in which the 
greater part of their course is situated. This is cer- 
tainly a very curious conclusion, and seems to justify 
the name canals as typifying a conduit of some sort 
in which something flowed. ^^ 

Passing strange as is the mere look of the canals. The canals 
study has disclosed something about them stranger ^harj^*^''^ 
yet : changes in their aspect depend on the time. 
Permanent the canals are in place, impermanent they 
prove in character. At one epoch they will be con- 
spicuous objects, almost impossible to miss ; then, a 
few months later, acuteness is taxed to discover them 
at all. Nor is this the whole story ; some will show 
when others remain hid, and others will appear when 
the first have become invisible. Whole regions are 
affected by such self-effacement or an equal ostenta- 
tion ; while neighboring ones are simultaneously 
given to the reverse. 

Curiously enough, the canals are most con- 
spicuous not at the time the planet is nearest to 
the earth and its general features are in consequence 
best seen ; but as the planet goes away, the canals 
come out. The fact is that the orbital position 
and the seasonal epoch conspire to a masking of 
the canal phenomena. For the planet comes to its 


closest approach to the earth a little before it 
reaches in its orbit the summer solstice of its south- 
ern hemisphere. For two reasons this epoch of 
nearness is an unpropitious date for the canal ex- 
hibit : first, because the bright areas, where the 
canals are easiest made out. He chiefly in the hemi- 
sphere then tipped away from the earth ; and 
secondly, because it is not the Martian season for 
the canals to show. 

Due to this inopportune occurrence of the two 
events, approach and seasonableness, the canals lay 
longer undetected by man than would otherwise 
have been the case. Something of the same in- 
felicity of appointment defeats the making of their 
acquaintance by many observers to-day. They look: 
at the wrong time. 
New method From their changes in conspicuousness it was 
o researc . gyident that the canals, like the large blue-green 
patches on the disk, were seasonal in their habit. 
To discover with more particularity what their law 
of change might be, an investigation to that end 
was conceived and undertaken at the opposition of 
1903, and in consequence a singular thing was 
brought to light. The research in question was the 
determination from complete drawings of the disk 
of the varying visibiHty of the several canals statisti- 
cally considered during a period of many months. 


For the making of the drawings extended over this 
time, and by a comparison of them one might note 
how any particular canal had altered in the interval. 
Their great number enabled accidental errors to be 
largely eliminated, and so assured a more trustworthy 
result. Systematic conditions affecting visibility — 
such as our own air, the position of the marking, 
and the size of the disk — were allowed for, so as 
to make the drawings strictly comparable. On the 
average, there were for each canal 100 drawings in 
which that canal either appeared or might have done 
so. And as 109 canals were considered in all, there 
resulted 10,900 separate determinations as basis for 
the eventual conclusion. 

The object now was to adopt some procedure by 
which this mass of material might be made to yield 
statistical information, not simply qualitative but 
quantitative results. Here the planet itself sug- 
gested a way. Owing to the rotation of Mars any 
region would be carried in and out of sight to an 
observer in space once in 24 hours and 40 minutes. 
But owing to an analogous rotation of the earth 
the observer himself is not always in a position to 
see. Furthermore, the two rotations are not quite 
synchronous and are besides complicated by the 
motions of the two planets in their orbits. The 
result is that there takes place a slow falling behind 


in the longitudes of Mars presented centrally to the 
earth at the same hour on successive nights. If we 
could only see the planet for a minute each night, 
we should think it to be slowly rotating backward 
at the rate of 9.6° of its own longitude a day. In 
consequence any given marking can only be well 
observed for about a fortnight consecutively, after 
which it passes off the disk at the hours suitable 
for observation, not to return again for a month. Its 
times of showing are called presentations. 

Now in the subject we are considering these 
presentations mark epochs six weeks apart at which 
the state of any marking may be examined in all 
the drawings in which it might then appear, a per- 
centage of visibility deduced for it and then the 
percentages for its several successive presentations 

By this method results may be got of quantita- 
tive value, capable of approaching something like 
exactitude from being each the mean of many 
observations, and observations made with an eye to 
no specific outcome — indeed, incapable of being so 
adapted in advance as the result showed. 

It is pleasing to note that to no one has the 
method commended itself more than to Schiaparelli. 
To welcome new procedures is the test of great- 
ness, for it betokens breadth of view. Most men's 


knowledge is cut on a bias of early acquisition, and 
cannot be adapted to new habits of thought. 

The percentages of visibility of the 109 canals at 
each of their presentations having thus been obtained, 
a tabulation of them showed what had been each 
canal's history during the period it was under obser- 
vation. From perusal of the table could be learned 
the canal's career, whether it had been a mere un- 
changing line upon the planet's disk, or whether for 
reason peculiar to itself it had varied during the 
interval. To show this the more easily, the per- 
centages were plotted upon coordinate paper, in 
which the horizontal direction should represent the 
time and the vertical the amount of the percentage. 
Then the points so found could be joined by a 
smooth curve, and the curve would instantly ac- 
quaint the eye with the vicissitudes of the canal's 
career from start to finish. The curve, in fact, 
would be its history graphically represented, and 
furthermore, would furnish a sign-manual by which 
it might be specifically known. The curve could be 
considered the canal's cartouche, — after the manner 
of the ideographs of the Egyptian kings, — sym- 
bolizing its achievements and distinguishing it at once 
from others. 

Since the height of the curve from the horizontal 
base to which it stood referred denoted the degree of 


visibility of the canal at the moment, any deviation in. 
this height along the course of the curve showed that 
the canal was then changing in conspicuousness from 
intrinsic cause. If the height grew greater, the canal 
was on the increase ; if less, it was on the decline. 
For precautions had already been taken to eliminate 
every circumstance, it will be remembered, which 
could affect the canal's appearance, except change in 
the canal itself 

Not only increase or decrease in the canal stood 
forth thus manifestly confessed, but any change in 
the rate of such wax and wane also lay revealed. 
In looking at them, one has only to remember that 
the action proceeds from left to right and that the 
ups and downs of the curve show exactly what that 
action was. 

Only one possible form out of them all indicates 
that no action at all was going on — the straight 
horizontal line. That cartouche signifies that its 
canal was a dead, inert, unchanging phenomenon for 
the period during which it was observed. 

Now, of all the 109 canals examined, only three 
cartouches came out as horizontal straight lines, and 
even these it is possible to doubt. This is a most 
telling bit of information. To begin with, it is an 
obiter dictum of the most subtly emphatic sort upon 
the reality of the canals. It states that the canals 

At the Telescope 
Experiments in Artificial Disks. 


cannot be optical or illusory phenomena of any kind 
whatsoever without in the least going out of its way 
to do so, as a judge might lay down some quite 
indisputable point of law in the course of a more 
particular charging of the jury. For an illusion 
could no more exhibit intrinsic change than a ghost 
could eat dinner without endangering its constitution. 
The mere fact that it is an illusion or optical product 
renders it incapable of spontaneous variation. Con- 
sequently, its cartouche would be a horizontal straight 
line. As the cartouches are not such lines, we have 
in them instant disproof of optical or illusory effects 
of every kind. 

Now, that the cartouches are curves shows that 
the action in them is not uniform, but increases or 
decreases more at one season than at another. 
Furthermore, as the curves both rise and fall in the 
course of their career, the action they typify must 
consist of alternate wax and wane. It is, therefore, 
periodic, which leads us again to the fact that it is 

Thus, to take the canal Ceraunius, we note that 
it dwindled from the time it was first observed, June 5 
in the Martian calendar, till about the end of June. 
It then started to increase in conspicuousness intrin- 
sically, in short to grow, until the early part of 
August, subsequently to which it again declined. 


vanishing after the first frost. Its cartouche further 
shows that its waning was a slow process of extinc- 
tion, its wax a relatively sudden one. 
Search for clew From the knowledge about the individual canal 
which the cartouches thus afford, we advance to what 
they prove capable of imparting by collective coor- 
dination with one another. To compare them it 
was necessary to select some point of the cartouche 

to decipher 

Days before sVL's?tce Days after %'^i2r 

-jO JO 60 go uo I /50 1 






! ^'^ 



Cartouche of the Ceraunius 

From a chart made by Professor Lowell. 

adapted to comparison purposes. The one that sug- 
gested itself was the point where the curve fell to 
a minimum. This point denoted the time at which 
each canal began to increase in conspicuousness, the 
dead point from which it rose. This dead point 
'was found for each cartouche, and starred on the 
curve. When this had been done and the cartouches 
tabled, at a first glance it seemed as if comparison 
were hopeless for the detection of any underlying 
principle and each cartouche only a law unto itself. 
But by recalling that the canals exist upon the 
surface of a globe and that the two directions for 


positioning a place upon a sphere are longitude and 
latitude, we are led to try latitude as the more 
promising of the two to furnish a clew. 

To this end the canals were segregated according 
to the zone on the planet in which they lay, and 
their separate values for consecutive times combined 
into a mean canal cartouche for the zone. This 
was done for all the zones, and the mean cartouches 
were then placed in a column descending according 
to latitude. 

The result was striking. Following down the Quickening of 
column, there is evident a delay in the time of '^^"^ ^^';^°''^- 

■' ^ ing to latitude. 

occurrence of the minimum as we descend the 
latitudes. This means that the canals started to in- 
crease from their dead point at successively later 
epochs in proportion to their distance from the 
planet's polar cap. 

Now, before seeking to put this symbolism into 
comprehensive terms, — to do which, I may add 
parenthetically, is just as scientific and far more 
philosophic than to leave the diagram as a cryptic 
monument of a remarkable law, which it were 
scientifically impious to interpret, — another fact ex- 
hibited by the diagram deserves to be brought out. 
It appears, if attention be directed to it, that in all 
the mean canal cartouches, the gradient is less be- 
fore the minimum than after it. What we saw to 


occur in the Ceraunius is the expression of a general 
law governing the canals. The curves fall slowly 
to their lowest points, and rise sharply from them. 
What this betokens will suggest itself on a moment's 
thought. It means that the effects of a previous 
motive force were slowly dying out in the first part 
of the curves, and then a fresh impulse started 
in to act. The new impulse was more instant 
and of greater strength in its action, and by piec- 
ing the two parts of the curve together, we con- 
clude that it was in both cases an impulse which 
acted fairly -quickly and of which the effects took a 
longer time to die out. The mean cartouches, then, 
assure us of two quickenings and lead us to infer 
that both were of the nature of forces speedily ap- 
plied and then withdrawn. 
^^uickening To interpret now the successive growth of the 

sarsa po ar ^^^^^j^ latitudinally down the disk is our next con- 
cern. We saw that it started at the edges of the 
polar cap. Now, such an origin in place at once 
suggests an origin of causation as well, and further- 
more precludes all other. For the origin of time 
was after the melting of the cap. First the cap 
melted, and then the canals began to appear. Those 
nearest to the cap did so first, and then the others 
in their order of distance from it, progressing in a 
stately march down over the face of the disk. 



Thus we reach the deduction that water liberated 
from the polar cap and thence carried down the disk 
in regular progression is the cause of the latitudinal 
quickening of the canals. A certain delay in the 
action, together with the amount of darkening that 
takes place, seems to negative the supposition that 
what we see is the water itself 

On the other hand, vegetation would respond only 
after a lapse of time necessary for it to sprout, — a 
period of, say, two weeks, — and such tarrying would 
account for the observed delay. 

Vegetation, then, explains the behavior of the 
canals. Not transference of water merely, but trans- 
formation consequent upon transference, furnishes 
the key to the meaning of the cartouches. Not 
the body of water, but the quickened spirit to which 
it gives rise, produces the result we see. Set free 
from its winter storage by the unlocking of the 
bonds of its solid state, the water, accumulated as 
snow, begins to flow and starts vegetation, which 
becomes responsible for the increased visibility of the 

Waked in this manner, the vegetal quickening, 
following the water with equal step, but only after 
due delay, passes down the disk, giving rise to those 
resuscitations we mark through the telescope, and 
attribute not without reason to seasonal change. 


Change it is, and seasonal as well, yet it is not what 
we know by the name in one important particular. 
For it is a vernal quickening peculiar to Mars which 
knows no counterpart on earth. 
The earth as To rcalize this, wc must try to see ourselves as 
fromTlce Others might see us. If we could do away with the 
cloud-envelope which must to a great extent shield 
our earth's domestic matters from prying astronomers 
upon other orbs, and selecting some coign of vantage, 
as, for example, Venus, scan the face of our familiar 
abode from a distance sufficient to merge the local 
in the general aspect, we should at intervals of six 
months notice a most interesting and beautiful trans- 
formation spread over it. It is the vernal flush of 
the earth's awakening from its winter's sleep that we 
should then perceive. Starting from near the hne 
of the tropic, we should mark the surface turn 
slowly virescent. As the tint deepened, we should 
see it also spread, creeping gradually up the latitudes 
until it stood within the Arctic Circle and actually 
bordered the perpetual snow. 

We should witness thus on the earth much what 
we mark on Mars at intervals twice as long, because 
there timed to the greater length of the Martian 
year. But one striking difference would be patent 
to the observer's eye : on earth the wave of 
wakening would travel from equator to pole ; on 


Mars It journeys from pole to equator. So much 
alike in their general detail, the two would thus be 
parted by the opposite sense of the action to a di- 
versity which at first would seem to deny any hke- 
ness in cause. To us the very meaning of seasonal 
change hinges on the return of the sun due to our 
change of aspect toward it. That the reverse could 
by any reason be ascribed to the same means might 
appear at first impossible. 

Not so when we consider it with care. Apart 
from the all-important matter of the seed, two fac- 
tors are concerned in the vegetal process, the absence 
of either of which is equally fatal to the result. The 
raw material, represented by oxygen, nitrogen, a few 
salts, and water, is one of these ; the sun's rays 
constitute the other. Unless it be called by the sun, 
vegetation never wakes. But, furthermore, unless it 
have water, it remains deaf to the call. Now, on 
the earth water is, except in deserts, omnipresent. 
The sun, on the other hand, is not always there. 
After its departure south in the autumn, vegetation 
must wait until its return in the spring. 

Mars is otherwise circumstanced. Dependent like Meitbg first 
us upon the periodic presence of the sun directly, it 
is further dependent upon the same source indirectly 
for its water-supply. Not having any surface water 
except such as comes from the annual unlocking of 



the snows of the polar cap, vegetation must wait 
upon this unlocking before it can begin to sprout. 


* - Dead Point of Vegefatian. 

Sprouting Times of Vegetation on the Earth 

The earth is represented upside down, in direct comparison with Mars as we see 
it in the telescope. 

From a chart made by Professor Lowell. 

The sun must have already gone north and melted 
the polar snows before vegetation starts, and when 


it starts, it must do so at the north, where the water 
arises, and then follow the frugal flood down the 
disk. Thus, if it is to traverse the surface at all 
with vegetation in its train, the showing must begin 
at the pole and travel to the equator. 

This, to us, inverse manner of vernal progression 
is precisely what the cartouches exhibit. Their curves 
of visibility show that the verdure wave is timed 
not primarily to the simple return of the sun, but 
to the subsequent advent of the water, and follows, 
not the former up the parallels, but the latter down 
the disk. 

It is possible to gauge the speed of the latitudi- Speed of 
nal sprouting of the vegetation, and therefore of the Ye'Ttation 
advent of the water down the canals, by the difl^er- 
ence in time between the successive darkenings of 
the canals of the several zones. Thus it appears 
that it takes the water fifty-two days to descend 
from latitude 72° N. to the equator, a distance 
of 2650 miles. This means a speed of 51 miles 
a day, or 2.1 miles per hour. 

So, from our study, it appears that a definite law 
governs the wax and wane of these strange things. 
Quickened by the water let loose on the melting of 
the polar cap, they rise rapidly to prominence, to 
stay so for some months, and then slowly proceed 
to die out again. Each in turn is thus affected, the 


march of vivification stalking the latitudes with steady- 
stride down the surface of the disk. Nothing stops 

I S Sab-T> -^j 
I iTtopiC 



i20 j.,^ jOO 

Sprouting Times of Vegetation on Mars 

From a chart made by Professor Lowell. 

its measured progress, or proves deterrent to its 
course. One after the other each zone in order is 
reached and traversed, till even the equator is crossed, 


and the advance invades the territory of the other 
side. Following in its steps afar, comes its slower 
wane. But already, from the other cap, has started 
an impulse of like character that sweeps reversely 
back again, travelling northward as the first went 
south. Twice each Martian year is the main body 
of the planet traversed by these antistrophic waves 
of vegetal awakening, grandly oblivious to everything 
but their own advance. Two seasons of growth it 
therefore has, one coming from its arctic, one from 
its antarctic, zone, its equator standing curiously be- 
holden semestrally to its poles.^^ 

There is something stirring to thought in this 
solidarity of movement, timed in cadence to the 
passage of the year. Silent as it is, the eye seems 
half to catch the measured tread of its advance as 
the darkening of the canals sweeps on in progressive 
unison of march. That it means life, not death, de- 
tracts no jot from the moving quality of its effect. 
For all its peaceful purpose, the rhythmic majesty 
of the action imposes a sense of power on the mind, 
seeming in some better way to justify the planet's 
name in its wholly Martian character. Called after 
the god of war, the globe is true to its character in 
the orderly precision of its stately processional change. 



ASTRONOMICAL discovery is of two kinds. If 
it consist simply in adding another asteroid or 
satellite to those already listed, obedience to the law of 
gravitation, with subsequent corroboration of place, 
alone is needed for belief. But if it relate to the detec- 
tion of an underlying truth as yet unrecognized, then 
it is only to be unearthed by reasoning on facts after 
they are obtained, and effects credence according to 
one's capacity for weighing evidence. Breadth of mind 
must match breadth of subject. For to plodders along 
prescribed paths a far view fails of appeal ; conserva- 
tive settlers in a land differ in quality from pioneers. 
Discovery of Discovcry of a truth in the heavens varies in 
truths similar nothing, cxccpt the subjcct, from discovery of a crime 
work. • on earth. The forcing of the secrets of the sky is, 
like the forcing of man's, simply a piece of detective 
work. It is the finding of a cause in place of a cul- 
prit ; but the process is quite similar. Causa criminis 
and causa discriminis differ only by a syllable. 

Like, too, are, or should be, the methods em- 


ployed. In astronomy, as in criminal investigation, 
two kinds of testimony require to be secured. Cir- 
cumstantial evidence must first be marshalled, and then 
a motive must be found. To omit the purpose as 
irrelevant, and rest content with gathering the facts, is 
really as inconclusive a procedure in science as in law, 
and rarely ends in convincing, any more than in 
properly convicting, anybody. For motive is just as 
all-pervading a preliminary to cosmic as to human 
events, only for lack of fully comprehending it we call 
the one a motive and the other a cause. Unless we 
can succeed in assigning a sufficient reason for a given 
set of observed phenomena, we have not greatly fur- 
thered the ends of knowledge and have done no more 
than the clerkage of science. A theory is just as 
necessary to give a working value to any body of facts 
as a backbone is to higher animal locomotion. It 
affords the data vertebrate support, fitting them for 
the pursuit of what had otherwise eluded search. 

Coordination is the end of science, the aim of all 
attempt at learning what this universe may mean. 
And coordination is only another name for theory, as 
the law of gravitation witnesses. Now, to be valid, a 
theory must fulfil two conditions : it must not be con- 
tradicted by any fact within its purview, and it must 
assign an underlying thread of reason to explain all 
the phenomena observed. Circumstantial evidence 


must first lead to a suspect, and then this suspect 
must prove equal to accounting for the facts. 

This method we shall pursue in the case before us ; 

and it will conduce to understanding of the evidence 

to keep its order of presentation to the detective in 

presenting it at the bar of reason. 

Review of the Starting with the known physical laws applicable to 

natura c am ^j^^ concentration of matter, we found that though in 

of evidence. ' o 

general the course of evolution of the earth and Mars 
was similar, the smaller mass of Mars should have 
caused it to differ eventually from the earth in some 
important respects. 

Three of these are noteworthy: (i) its surface 
should be smoother than the earth's, (2) its oceans 
relatively less, (3) its air scantier. On turning to Mars 
itself we then saw that these three attributes of the 
planet were precisely those the telescope disclosed, 
(i) The planet's surface was singularly flat, being 
quite devoid of mountains ; (2) its oceans in the past 
covered at most three-eighths of its surface instead of 
three-quarters, as with us ; (3) its air was relatively 
Aspect of We next showed that physical loss should, from 

arscorroo- -^^ smaller mass, have caused it to age quicker, and 

rates principles o i -' 

of planetary that this aging should reveal itself by the more com- 

evolution. . . r i • j j 

plete departure or what oceans it once possessed and 
by the wider spread of deserts. 


Telescopic observation we then found asserted these 
two pecuharities : (i) no oceans now exist on the 
planet's surface ; (2) desert occupies five-eighths of it. 

From such confirmation of the principles of planet- 
ary evolution from the present aspect of the planet 
Mars, we went on to consider the two most essen- 
tial prerequisites to habitabihty : water and warmth. 
Water we sought first ; and we found it in the polar 
caps. The phenomena of the polar caps proved ex- 
plicable as consisting of water, and not as of anything 
else. Still more important was the question of tem- 
perature. We took this up with particularity. We 
found several factors to the problem not hitherto 
reckoned with, and that when these were taken into 
account the result came out entirely different from 
what had previously been supposed. Instead of a 
temperature prohibitive to life, one emerged from our 
research entirely suitable for it. And this even more 
for animals than plants. For a climate of extremes 
was what that of Mars appeared to be, with the 
summers warm. Now, investigations on earth have 
shown that it is the temperature of the hottest season 
that determines the existence of animals, cold much 
more adversely affecting plants. Yet to the presence 
of the latter the look of the disk conformed. Scan- 
ning it, we marked effects which could only be ex- 
plained as vegetation. Thus the conditions on Mars 


Animal life 
disclosed only 
by mind. 

Canals con- 
front the 

showed themselves hospitable to both great orders of 
life, the latter actually revealing its presence by its 
seasonal changes of tint. 

Here we reached the end of what might directly be 
disclosed in the organic economy of the planet. For 
at this point we brought up before a most significant 
fact: that vegetable life could thus reveal itself directly, 
but that animal life could not. Not by its body, but 
by its mind, would it be known. Across the gulf of 
space it could be recognized only by the imprint 
it had made on the face of Mars. 

Turning to the planet, we witnessed a surprising 
thing. There on the Martian disk were just such 
markings as intelligence might have made. Seen even 
with the unthinking eye, they appear strange beyond 
belief, but viewed thus, in the light of deduction, they 
seem positively startling, like a prophecy come true. 

Confronting the observer are lines and spots that 
but impress him the more, as his study goes on, with 
their non-natural look. So uncommonly regular are 
they, and on such a scale, as to raise suspicion whether 
they can be by nature regularly produced. Next to 
one's own eyesight the best proof of this is the un- 
solicited indorsement it has received in the scepticism 
their depiction invariably evokes. Those who have 
not been privileged to see them find it well-nigh im- 
possible to believe that such things can be. Nor is 


this in the least surprising. But however consonant 
with nescience to doubt the existence of the lines on 
this score, to do so commits it to witness against itself 
of the most damaging character the moment their exist- 
ence is proved. Now, assurance of actuality no longer 
needs defence. The lines have not only been amply 
proved to exist, but have actually been photographed, 
and doubt has shifted its ground from existence to 
character, a half retreat tantamount to a complete sur- 
render. For without equal investigation, to admit a 
discovery and deny its description is like voting for a 
bill and against its appropriation. It reminds one of 
the advice of the old lawyer to a junior counsel : 
^' When you have no case, abuse the plaintiff's 

Unnatural regularity, the observations showed, 
betrays itself in everything to do with the lines : in 
their surprising straightness, their amazing uniformity 
throughout, their exceeding tenuity, and their im- 
mense length. These traits, instead of disappearing, 
the better the canals have been seen, as was confidently 
prophesied, have only come out with greater insistence. 
With increased study not only the assurance gains that 
they are as described, but a mass of detail has been 
added about them impossible to reconcile with any 
natural known process. 

A sing^le instance of the methodism that confronts 



us will serve to make this plain. The Lucus Ismenius 
is a case in point. The marking so called consists of 
two round spots each about seventy-five miles in 

diameter. They lie close 
together, not more than 
fifty miles of ochre ground 
parting their peripheries. 
Into them converge a 
number of canals — seven 
doubles and five singles. 
Now, the manner of these 
meetings is curiously de- 


TEMATic Method in which the 

Double Canals enter the Twin doubles embrace the oases, 

just enclosing them be- 
tween their two arms. The 
four other doubles send a 
line to each oasis to enter 
it centrally. Which con- 
nection the double shall 
adopt apparently depends 
upon the angle at which 
the approach Is made. If the direction be nearly 
vertical to the line of the two oases, the entrance 
is central ; if parallel, it is an embrace. As for the 
singles, they connect with one or the other oasis, 
as the case may be. Such precise and methodical 

1. Euphrates, double. 

2. Hiddekel, double. 

3. Protonilus, double. 

4. Deuteronilus, double. 

5. Astaboras, double. 

6. Djihoun, double. 

7. Arnon, convergent double. 

8. Aroeris. 9. Sados. 
10. Pallacopas. 11. Phthuth. 

12. Naarmalcha, double. 

13. Naarsares. 



arrangement, thus marvellously articulated and de- 
tailed, discloses an orderliness so surprising, if on 
nature's part, as to throw us at once into the arms of 
the alternative as the least astonishing of the two. 

Before passing on Not rivers. 

to reason upon the 
fact, we note that 
the characters men- 
tioned are them- 
selves enough to 
negative all sup- 
positions of natural 
cause. First, the 
lines cannot be 
rivers, since rivers 
are never straight 

^ From a drawing by Professor Lowell. 

and never uniiorm ^^^ Moon, showing the Straight Wall 

in width. Now we ^^^ ^^^^ "^^ ™^ ^^^^"^ ^^ ^^^^' ^^^^' 

see the canals so ^, 1 ui 1 n .u ■ •,- 

These are palpable cracks like those m a ceilmg, 
well as to be nuite ^"*^ quite unhke the uniform canal lines of 

^ Mars. 

certain of their even- 
ness. The best proof of this is that, though each is 
uniform, some are at least ten times the size of others. 
If one of them dwindled en route, we should have 
ample measure of the fact. 

Nor can the lines be cracks in the surface, because Not cracks. 
cracks also are not straight, and because cracks end 

. , - ^-^ 


■ 'J 

\ '"^ 



before finishing. We have examples of undoubted 
cracks in more than one heavenly body, and their 
appearance is quite unlike the look of the lines of 
Mars. The moon offers such in many, if not all, of 
her so-called rills. 

To the most superficial view these suggest their 
nature, but when carefully examined at Flagstaff, 
corroboration of the fact came out in certain definite 
characteristics. For the rills proved to be made of 
parts which overlapped at their ends, one fractional 
line taking up the course before the other had given 
out, thus exactly reproducing the composition of the 
cracks in any plaster ceiling. 

Mercury bears testimony to the same effect. Its 
lines, more difficult than the canals of Mars, — for 
we see Mercury four times as far off when best 
placed as we do Mars, — though roughly linear, are 
not unnatural in appearance even at that great dis- 
tance, and show irregularities suggestive of cracks.* 
In the markings on Venus, too, there is nothing 
Other natural Rivcrs and cracks are the two most plausible sup- 
exp ana ions positions made to account for the lines on any theory 

prove impos- a J ■' 

sibie. of natural causation. Other guesses have been in- 

* Lately, at least -two critics have stated that the descriptions of the spoke-like 
markings seen on Venus at Flagstaff in 1897 and later, are inconsistent. The seeming 
inconsistency is due to our own air, which sometimes defines them, sometimes not. 
The important point about them is that the Venusian lines are irregular. — P. L. 



be 43 

(U T) 

bx) o 

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(U 0) " -'-' 

c o <u -a 

5 ■S 5 JJ 

o -a 

^ i^; -^ oj 

t/J CS j_, .^ 

U) 1/2 1^ u- 

^ ii •£ o 

"^ ^ ^ G 

a a-^ .0 

o 1^ -a t: 

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+- r-' c« a. 


dulged in, such as that meteors by their passing 
attraction have raised the lines as welts upon the 
surface — welts easily allayed by application of the 
fact that the lines change with the seasons, actually 
disappearing at certain epochs, to revive again at 
others. Such suggestions there are, but none have 
been advanced to my knowledge that bear the most 
cursory inspection. 

Still more inexplicable on any natural hypothesis 
is the systematized arrangement of the lines to form 
a network over the whole planet. That the lines 
should go directly from certain points to certain 
others in an absolutely unswerving direction ; that 
they should there meet lines that have come with 
like directness from quite different points of depar- 
ture ; that sometimes more than ten of them should 
thus rendezvous, and rarely less than six ; and that, 
lastly, this state of intercommunication should be 
true all over the disk, are phenomena that no natural 
physical process that I can conceive of — and no 
one else seems to have been able to, either — can 
in the least explain. Yet this arrangement cannot 
be due to chance, the probabilities against the lines 
meeting one another in this orderly manner being 
millions to one. 

Oases equally But the canals are not all that is wonderful ; 

inexplicable. ^^ j^^^^ ^^ Tcckon with the oases as well. These 


are remarkable, both in themselves and in their re- 
lation to the system of lines ; for they occur at the 
junctions — only at the junctions, and virtually al- 
ways at the junctions. They are thus of the nature 
of knots to the network. No explanation can be 
given of this by purely physical laws. 

So we might go on, with the enigma of the double 
canals more and more mysterious the more one learns 
about them — with 
their strange posi- 
tioning on the planet 

in the tropical belts ; ' . *" ' 

with the curious ^"^^^'^ \ 

phenomenon of con- 4 

verging or wedge- 
shaped doubles de- 
scending to join ^-m 
them from the pole ; 

and with other facts ^ corner of mars, June 10, 1907 

equally odd. 

But long before the catalogue of geometric Artificiality 

. . , , , . , - . suggests itself. 

curiosities had drawn to its close, — tor it were 
wearisome to count them all, and where even one 
is so cogent, numbers do not add, — it becomes 
apparent to any one capable of weighing evidence 
that these things which so palpably imply artificiahty 
on their face cannot be natural products at all, but 




that the observer apparently stands confronted with ' 
the workings of an intelligence akin to and there- 
fore appealing to his own. What he is gazing on 

typifies not the out- 
come of natural 
forces of an ele- 
mental kind, but the 
artificial product of a 

mind directing it to 

Arethusa Lucus, April 15, 1903, showing 

Converging Canals from the North 3, purposed and derl- 

^^^^^ ^^^ nite end. 

When once this standpoint is adopted, we begin 
to see light. The recognition of artificiality puts 
us on a track where we gather explanation as we 
Great-circle Thus two attributes, onc of the canals, the other 

the canals ^^ ^^^ oascs, find explanation at once. The great- 
circle directness of the lines stands instantly inter- 
preted. On a sphere a great circle takes the 
shortest distance between two points. It offers, 
therefore, the most expeditious route from one place 
to another. It is, then, that which, when possible, 
intelligence would adopt. Even in the case of our 
very accidented earth, our lines of communication 
are being rectified every year as we progress in 
mastery of our globe. 

Equally suggestive is the shape of the oases, or 



spots, that button the Hnes together. For they circularity 
show round. Now, a solid circle has the peculiar 
property that the average distance from its centre 
to all points in it is less than for any figure enclos- 
ing a like area. It would be the part of intelli- 
gence, then, to construct this figure whenever the 
greatest amount of ground was to be reached for 
tillage or any other purpose at the least expendi- 
ture of force. 

No less telltale is their behavior ; and now not 
only of the bare fact of artificiality, but of the 
manner in which it came to be. 

The extreme threads of the world-wide network Note of water 
of canals stand connected with the dark-blue patches '"''"^^J^^'s 

X the action. 

Canals from the South Polar 
Cap, the White Bonnet at 
THE Top of the Picture, 
June 6, 1907 
Martian date, September 22. 

Canals from the South Polar 
Cap, Shown at the Top of 
THE Picture, October 25, 

Martian date, December 18. 

at the edge of one or the other of the polar caps. 
But they are not always visible. In the winter 
season they fail to show. Not till the cap has 


begun to melt, do they make their appearance, and 
then they come out dark and strong. Now, the 
cap in winter is formed of snow and ice that melts 
as summer comes on. Here, then, the attentive 
ear seems to catch the note of running water. 

From their poleward origin the lines begin to 
darken down the disk. One after the other takes 
up the thread of visibility, to hand it on to the next 
in place. So the strange communication travels, 
carried from the arctic zone through the temperate 
and the tropic ones on to the equator, and then be- 
yond it over into the planet's other hemisphere. A 
flow is here apparent, journeying with measured 
progress over the surface of this globe. Here, again, 
the mental ear detects the sound of water percolat- 
ing down the latitudes. 

Across what once were seas, but are seas no more, 
the darkening of the lines advances, with the same 
forthrightness as over the ochre continental tracts. 
Blue-green areas of vegetation and arid wastes alike 
are threaded by the silent deepening of tint. Lati- 
tude bars .it not, nor character of country. It 
great-circles the old sea bottoms as cheerfully as it 
caravans the desert steppes. This persistency made 
possible by the loss of what the seas once held, the 
thought of water is once more thrust upon the 
sense, its absence now as telling as its presence was 



before. One hears it in the very stillness the lack 
of it promotes. 

Then, as with quickened sense one listens, the 
mind is aware of antiphonal response in the unlock- 
ing of the other cap to send its scanty hoardings 
in similar rilling over the long-parched land. The 
note of water confronts us thus at every turn of 
this strange action. Water, then, must be the 
word of the enigma : the clew that will lead us to 
the unloosening of the riddle. 

But though water it be, this is not the complete its locomo- 

. 1 . r 1 11 r 1 1 tion explained. 

solution or the problem ; tor, as one ponders, the 
unnatural character of the action dawns on one. 
That a wave of progression passes through the 
canals down the disk ; that something, then, pro- 
ceeds from the pole to the equator ; and that this 
something can be none other than water, giving rise 
to vegetation, sounds simple and forthright. The 
startling character of the action is not at once 
apparent. It becomes so only when we try to 
account for the locomotion. When we so envisage 
it, the transference turns out to be a most astound- 
ing and instructive thing. 

■ To understand wherein lies its pecuharity, we must 
consider the shape of the planet. For the planet is 
flattened at the poles by ^-^ of its diameter. This, to 
begin with, will make the action seem even stranger 


than it is. It might seem at first as if the water in 
going to the equator had to run twenty-one miles 
Mars' surface If Mars did not rotate, its figure would be a 

in fluid equi- r i • i r • 

librium. sphere, except for such tidal deformation as outside 

bodies might give it, because its own gravity would 
pull it into a shape similar in all directions. As 
Mars rotates, its rotatory momentum bulges it at 
the equator, changing the sphere into what is called 
an oblate spheroid of the general form of an 
orange. The ellipticity of a rotating mass is affected 
not only by the size of the body and by the speed 
of rotation, but by the distribution of the matter 
, composing it. Thus it is different for a homo- 
geneous body than for a heterogeneous one, and 
differs according to the law of density from surface 
to centre. Now it is an interesting fact that the 
oblateness of Mars — y^-qj found by two indepen- 
dent methods quite independently applied ; one 
from measurements of the planet made in 1894 at 
Flagstaff by Mr. Douglass, reduced and discussed 
by the director ; the other from the motions of the 
satellites by Hermann Struve — should fall between 
the value it would have, were it- homogeneous, and 
that which it would show did the density increase from 
surface to centre in the same manner as on earth. 
But we can see from theory that it should lie be- 


tween these two extremes. For the compression 
there is not so great as with the earth because of 
Mars' smaller mass. In this we find another proof, 
were any needed, that the evolution of both planets 
was as sketched in our opening chapter. A rapidly 
rotated mass of putty will take on the same shape. 
In the case of Mars the stresses are so enormous 
that for a long acting force, such as is here con- 
cerned, the planet, although probably as rigid as 
steel, behaves as if its mass were plastic. The 
result is that the direction of gravity is always per- 
pendicular to the surface at every point; or, in 
other words, the surface is in stable equilibrium. 

Now, the fact that every point of the surface is Gravity in- 
in equihbrium means that any particle of a liquid ^^p^^^^°^ 

^ ^ ■*■ ^ water trans- 

there — as, for example, a drop of water — would ference. 
not move, but would stay where it was. For all 
the forces being exactly balanced to rest, their 
resultant cannot solicit it to stir. Just as on the 
surface of the earth, water upon a level stretch of 
ground shows no tendency to move. 

Consequently, any water set free near the pole 
by the melting of the polar cap would stay where 
it was liberated without the least inclination to go 
elsewhere. The only force which would have the 
slightest effect upon it might be its own head, if it 
had any. Were the melting ice or snow that gave 


birth to it ten feet thick, and it is more likely to be 
less, it would give rise to an average head of water 
of five feet. Now, a head of five feet could not 
urge the water against surface friction more than a 
few miles at most. So that any such impulse is 
quite impotent to the effects we see. 

Face to face, then, we find ourselves with a mo- 
tion of great magnitude occurring without visible or 
physically imaginable cause. A body of water travels 
3300 miles at the rate of 51 miles a day under no 
material compulsion whatever. 

It leaves the neighborhood of the pole, where it 
was gravitationally at home, and wanders to the 
equator, where gravitationally it was not wanted, 
without the slightest prompting on the part of any 
natural force. The deduction is inevitable; it must 
have been artificially conducted over the face of the 
planet. We are left no alternative but to suppose 
it intelligently carried to its end. 

Nor is this the hmit " of the extraordinary per- 
formances shown by the progressive darkening of 
the canals down the disk. Were they actuated by 
natural forces, what they next do would be simply 
incredible. For, not content with descending to the 
equator without visible means of propulsion, once 
arrived there, they promptly proceed to cross it into 
the planet's other hemisphere and run up the lati- 



tudes with equal celerity on the other side. Now, 
any physical inducement given them to come equa- 
torward must have its action reversed so soon as 
that dividing-line was crossed. If, then, they were 
in any way helped to the earlier part of their pere- 
grination by natural 
forces, they would be 
hindered by them in 
this latter portion of 
their career. Thus, the _ 


only rational result of The " original" canal leaves from the tip 
our discussion of the of the ^/..., the "duplicate" frorx. 

higher up its coast. 

canals is that these 

things are not dependent on natural forces for their 
action, but are artificial productions designed to the 
end they so beautifully serve. In the canals of the 
planet we are looking at the work of local intelligence 
now dominant on Mars. Such is what the circum- 
stantial evidence points to unmistakably. 

To detection of a motive we now turn. And 
here it is our study of planetary evolution in gen- 
eral becomes of service. As a planet ages, its sur- 
face water grows scarce. Its oceans in time dry up, 
its rivers cease to flow, its lakes evaporate. Its fauna, 
if it have any, dependent as they are upon water for 
life, must more and more be pushed to it for that 
prime necessity to existence. 


As the water leaves a planet, departing into space, 
so much of it as does not sink out of sight into its 
interior stands for a while a-tiptoe in its air before 
taking final flight into the sky. In the planet's 
economy it has ceased to be water, and become that 
more ethereal thing, water-vapor. In one way and 
place only does it ever in any amount descend to 
earth again and take on even transiently its liquid 
state. This is in the polar caps. The general mete- 
orologic circulation of the planet deposits it there 
throughout the winter months. From the cold of 
the arctic latitudes its deposition takes the form of 
snow or ice, and in consequence of this solid state 
is largely tethered to the spot where it falls, remain- 
ing in situ until the returning sun melts it in the 
spring. This is the state of things on Mars. 

When this unlocking occurs, and while the water 
is in its intermediate liquid state, between not easily 
transportable ice and ungatherable vapor, it is in a 
condition to be moved, and may be drawn upon for 
consumption. Then, and then only, is it readily 
available for use, and then, if ever, it must be 

Now, in the struggle for existence, water must be 
got, and in the advanced condition of the planet this 
is the only place where it is in storage and whence, 
therefore, it may be had. Round the semestral release 


of this naturally garnered store everything in the 
planet's organic economy must turn. There is no 
other source of supply. Its procuring depends upon 
the intelligence of the organisms that stand in need 
of it. If these be of a high 
enough order of mind to divert 
it to their ends, its using, from 
a necessity, will become a fact. \ / jj 

Here, then, is a motive of the 

most compelhng kind for the 

, • r . 1 1 J 4.U Differentiation of the 

tappmg or the polar caps and the 

leading of the water they contain The Ca^^es is the double 

over the surface of the planet: -:\/:^:^J7r;>,: 

the primal motive of self-preser- ^^"^"^ °^ *^ ^'^^- ^* 

-'■ ^ will be noticed that the 

Vation. No incentive could be right-hand line is stronger 

than the left-hand one. 

Stronger than this. 

Our motive found being of the most drastic kind, 
it remains now to examine whether it can be put 
into execution. 

As a planet ages, any organisms upon it would organisms 
share in its development. They must evolve with ^^"'^^^^^ 

i J planet ages. 

it, indeed, or perish. At first they change only as 
environment offers opportunity, in a lowly, uncon- 
scious way. But, as brain develops, they rise su- 
perior to such occasioning. Originally the organism 
is the creature of its surroundings ; later it learns to 
make them subservient to itself. In this way the 


organism avoids unfavorableness in the environment, 
or turns unpropitious fortune to good use. Man 
has acquired something of the art here on the earth, 
and what with clothing himself in the first place, and 
yoking natural forces in the second, lives in comfort 
now where, in a state of nature, he would inconti- 
nently perish. 

Such adaptation in mind, making it superior to 
adaptation in body, is bound to occur in the organic 
life on any^ planet, if it is to survive at all. For 
conditions are in the end sure to reach a pass where 
something more potent than body is required to cope 
with them. 
One species It is possiblc to apply a test to tell whether 

supplants all i i-r • i r^ • • i i i 

others. such lite existed or not. I^or certain signs would be 

forthcoming were such intellect there. Increase of 
intelligence would cause one species in the end to 
prevail over all others, as it had prevailed over its 
environment. What it found inconvenient or un- 
necessary to enslave, it would exterminate, as we have 
obliterated the bison and domesticated the dog. This 
species will thus become lord of the planet and 
spread completely over its face. Any action it might 
take would, in consequence, be planet-wide in its 

Now, such is precisely what appears in the world- 
spread system of canals. That it joins the surface 


from pole to pole and girdles it at the equator be- 
trays a single purpose there at work. Not only does 
one species possess the planet but even its subdivi- 
sions must labor harmoniously to a common aim. 
Nations must have sunk their local patriotisms in a 
wider breadth of view and the planet be a unit to the 
general good. 

As the being has conquered all others, so will it at To die of 
last be threatened itself. In the growing scarcity of ^ "^'^* 
water will arise the premonitions of its doom. To 
secure what may yet be got will thus become the 
forefront of Its endeavor, to which all other questions 
are secondary. Thus, if these beings are capable of 
making their presence noticeable at all, their great 
occupation should be that of water-getting, and 
should be the first, because the most fundamental, 
trace of their existence an outsider would be privi- 
leged to catch. 

The last stage in the expression of life upon a 
planet's surface must be that just antecedent to its 
dying of thirst. Whether it came to this pass by 
simple exhaustion, as is the case with Mars, or by 
rotary retardation, as is the case with Mercury and 
Venus, the result would be all one to the planet 
itself Failure of its water-supply would be the 
cause. To procure this indispensable would be its 
last conscious effort. 


End foreseen. " With ail intelligent population this inevitable end 
would be long foreseen. Before it was upon the 
denizens of the globe, preparations would have been 
made to meet it. And this would be possible, for 
the intelligence attained would be of an order to cor- 
respond. A planet's water-supply does not depart 
in a moment. Long previous to any wholesale im- 
minence of default, local necessity must have begun 
the reaching out to distant supply. Just as all our 
large cities to-day go far to tap a stream or a lake, 
so it must have been on Mars. Probably the be- 
ginnings were small and inconspicuous, as the water 
at first locally gave out. From this it was a step 
to greater distances, until necessity lured them even to 
the pole. The very process, one of addition, in- 
stead of one of total synchronous construction, seems 
to show stereotyped to us in the canals. These run 
in their fashioning rather with partial than with tele- 
ologic intent, giving as much concern to halfway 
points as to the goal itself, although in their action 
now they are totally involved. The thing was not 
done in a day, and by that very fact stamps the 
more conclusively its artificial origin. 

The ability of beings there to construct such 
arteries of sustenance, two considerations will help 
to make comprehensible : one of these minifies the 
work, the other magnifies the workers. In the first 

i-< ON 
X 00 



place, it is not what we see that would have to be 
constructed. The object of endeavor is not only the 
water itself, but the products that water makes pos- 
sible. It is vegetation which is matter of imme- 
diate concern, water being of mediate employment. 
This, then, is what would probably show. Just as 

Northeast Corner of Aeria, July 2-5, 1907 

on the earth it is the irrigated strip of reclaimed 
desert, and not the Nile itself, which would make 
its presence evident across interplanetary space. If 
these lines are irrigated bands of planting, the ver- 
tebral canal would be a mere invisible thread in the 
midst of that to which it gave growth. This alone 
would have to be made, and indeed it would prob- 
ably be covered to prevent evaporation. 


Now, we have evidence that the canals are thus 
composed of nerve and body. When they He down,, 
they do not entirely vanish. Under the visual con- 
ditions of Flagstaff they may still be made out in 
their dead season, the mere skeletons of themselves 
as they later fill out. And even so we do not ac- 
tually see the nerve itself. 

For the construction of these residuary filaments, 
we have a plethora of capabilities to draw upon : in 
the first place, beings on a small planet could be 
both bigger and more effective than on a larger one,, 
because of the lesser gravity on the smaller body.. 
An elephant on Mars could jump like a gazelle. 
In the second place, age means intelligence, enabling^ 
them to yoke nature to their task, as we are yoking 
electricity. Finally, the task itself would be seven 
times as light. For gravity on the surface of 
Mars is only about 38 per cent of what it is on 
the surface of the earth ; and the work which can 
be done against a force like gravity with the same 
expenditure of energy is inversely as the square of 
that force. A ditch, then, seven times the length 
of one on earth could be dug as easily on Mars. 

With this motive of self-preservation for clew, and 
with a race equal to the emergency, we should ex- 
pect to note certain general phenomena. Both polar 
caps would be pressed into service in order to utilize 


the whole available supply and also to accommodate 
most easily the inhabitants of each hemisphere. We 
should thus expect to find a system of conduits of 
some sort world-wide in its distribution and running 
at its northern and southern ends to termini in the 
caps. This is precisely what the telescope reveals. 
These means of communication should be, if possible, 
straight, both for economy of space and of time, it 
being especially necessary to avoid any wasteful 
evaporation on the road. Construction of such would 
needs be very difficult, if not impracticable, on earth, 
owing to the often mountainous character of its sur- 
face. But on Mars this is not the case. As we have 
seen, there are fortunately no mountains on Mars. 
Thus the great obstacle to canals, and, in conse- 
quence, the great obstacle to their acceptance, is 
providentially removed. Terrain offers the least of 
objections, terror the greatest of spurs, to their con- 

Thus we see that not only should the execution 
be possible, but that it should exhibit precisely the 
phenomena we see. 

It would be interesting, doubtless, to learn how Further 
are bodied these inhabitants that analysis reaches out ^ ^"°"^^"^- 
to touch. But body is the last thing we are likely 
to know of them. Of their mind as embodied in 
their works, we may learn much more ; and, after all. 


is not that the more pregnant knowledge of the two ? 
Something of this we have surveyed together. But 
beyond the lime-hght of assured deduction stand 
many facts awaiting their turn to synthetic coordina- 
tion which we have not touched upon. It is proper 
to mention some of them under due reserve, for 
they constitute the bricks which, with others yet to 

The Carets of Mars 

Carets at the borders of the " seas " ; showing those of Icarii Luci and their resem- 
blance, in miniature, to the two forks of the Sabaeus Sinus. These carets are 
distinctive phenomena, marking the entrance of the canals from the dark 
regions into the light. They are found at such points, and at such points only. 

come, will some day be built up into a housing 

Not least of these are those strange caret-shaped 
dark spots at the points where the canals leave the 
dark regions to adventure themselves into the light. 
No canal thus circumstanced in position is apparently 
without them, and, unHke the oases, they do not 
show round. On the theory of canalization they are 



certainly well placed. We have seen that the blue- 
green regions and the ochre ones lie undoubtedly 
at different levels, the former standing much lower 
than the latter. 

Here, then, should occur difficulties in canalization 
which would have to be overcome. Are these, then, 
the evidence of their 
surmounting ? They 
certainly suggest the 

Then the oases 
themselves lure our 
thoughts afield. Im- 
portant centres to the 
canal system they are 
on their face. But, if centres to that, they should 
bear a like relation to what fashioned the canals. 
That they dilate and dwindle seasonally points to 
vegetation as their chief constituent, whence their 
name. But behind, and informing this, must be the 
bodied spirit of the whole. We are certainly justi- 
fied in regarding them as the apple of the eye of 
Martian life — what corresponds with us to centres 
of population. 

An interesting phenomenon about the oases makes 
this the more probable. Observation discloses that 
the oases are given to change both of size and tone. 

Mouths of Euphrates and Phison 

The drawing shows the way in which each 
branch of the two double canals enters the 
desert from a common point of departure. 


They fade at certain seasons, retaining only a rela- 
tively diminutive dark kernel. They are thus formed 
of two parts, pulp and core. The pulp itself indi- 
cates vegetation, since it follows the same laws as the 
canals ; the core may well be the evidence of the 
permanent population. That the largest are some 
75 miles across, seems to give sufficient space 
for living and the means to live. If our cities 
had to be their own sources of supply, they might 
well be of this size. As it is, Tokio is ten miles by 
ten, and London yet larger. But we must in this 
be careful to part surmise from deduction. 
Speculation In our cxposition of what we have gleaned about 

Mars, we have been careful to indulge in no specula- 
tion. The laws of physics and the present knowl- 
edge of geology and biology, affected by what 
astronomy has to say of the former subject, have 
conducted us, starting from the observations, to the 
recognition of other intelligent life. We have care- 
fully considered the circumstantial evidence in the 
case, and we have found that it points to intelli- 
gence acting on that other globe, and is incompatible 
with anything else. We have, then, searched for 
motive and have lighted on one which thoroughly 
explains the evidence that observation offers. We 
are justified, therefore, in believing that we have un- 
earthed the cause and our conclusion is this : that we 



have in these strange features, which the telescope 
reveals to us, witness that life, and life of no mean 
order, at present inhabits the planet. 

Part and parcel of this information is the order of 
intelligence involved in the beings thus disclosed. 
Peculiarly impressive is the thought that life on an- 
other world should thus have made its presence 
known by its exercise of mind. That intelHgence 
should thus mutely communicate its existence to us 
across the far stretches of space, itself remaining hid, 
appeals to all that is highest and most far-reaching 
in man himself. More satisfactory than strange this; 
for in no other way could the habitation of the 
planet have been revealed. It simply shows again 
the supremacy of mind. Men live after they are 
dead by what they have written while they were alive, 
and the inhabitants of a planet tell of themselves 
across space as do individuals athwart time, by the 
same imprinting of their mind. 

Thus, not only do the observations we have Our life not 
scanned lead us to the conclusion that Mars at this ""^*i"^- 
moment is inhabited, but they land us at the further 
one that these denizens are of an order whose ac- 
quaintance was worth the making. Whether we 
ever shall come to converse with them in any more 
instant way is a question upon which science at 
present has no data to decide. More important to 


us is the fact that they exist, made all the more 
interesting by their precedence of us in the path of 
evolution. Their presence certainly ousts us from 
any unique or self-centred position in the solar sys- 
tem, but so with the world did the Copernican 
system the Ptolemaic, and the world survived this 
deposing change. So may man. To all who have 
a cosmoplanetary breadth of view it cannot but be 
pregnant to contemplate extra-mundane life and to 
realize that we have warrant for believing that such 
life now inhabits the planet Mars. 
Martian life A saddcr interest attaches to such existence : that 

it is, cosmically speaking, soon to pass away. To 
our eventual descendants life on Mars will no longer 
be something to scan and interpret. It will have 
lapsed beyond the hope of study or recall. Thus to 
us it takes on an added glamour from the fact that 
it has not long to last. For the process that 
brought it to its present pass must go on to the 
bitter end, until the last spark of Martian life goes 
out. The drying up of the planet is certain to 
proceed until its surface can support no life at all. 
Slowly but surely time will snuff it out. When the 
last ember is thus extinguished, the planet will roll 
a dead world through space, its evolutionary career 
forever ended. 

nearing its 




On Moment of Momentum 

The momentum of a body is the quantity of motion it 
contains, which is its mass multipHed by its velocity, i.e. 
the sum of the motions of all the particles composing it. 
Its moment of momentum about any point is this quantity 
into the perpendicular from the point upon its instanta- 
neous course. It is thus 

where m is its mass ; 

V its velocity at right angles to the shortest distance 

to the point ; 
r its perpendicular distance from the point. 
Suppose, now, two bodies, one x times the mass of the 
other, to be revolving round each other in circles and, for 
simplification, that both are homogeneous and non-rotating. 
If m be their united mass, the relative velocity of one 
about the other is 

v^ = khni ) — - k"^— 

\r a) r 

for a circular orbit, k'^ being the unit force at unit distance. 
Then the moment of momentum of the system round its 
centre of gravity is 

{i—x)m • — ^— p • — r-\-mx • ^^ '- — k—^ • ^^ '— - r 

m r* m in r^ m 

since the velocities of the bodies about their centre of 
gravity and their distances from it are inversely as their 


To find what partition renders this quantity a maximum, 
we must differentiate it with regard to x and put the deriv- 
ative equal to zero. Thus 

-^ y — ^ '-^ = ^= I — 2;ir = o; 

dx dx 

whence x = ^, or the masses must be equal. That this 
gives a maximum is shown by the second derivative, 

d{i — 2x) _ _ 

Applying this to Jupiter and the Sun, we see that the 
moment of momentum of the two is only ^^o of what it 
might be were the mass otherwise distributed to get the 
greatest effect. In other words, the quantity of motion in 
the solar system is almost the least possible ; and from the 
principle of the conservation of the moment of momentum 
of a system of bodies by their mutual action, .this has 
always been so. 

For the system a Centauri, though the mass of its two 
suns is only 2.14 that of the Sun's, the moment of momen- 
tum is about 2000 times as great. 

The Connection of Meteorites with the Solar 

The speed with which meteorites are observed to enter 
the Earth's atmosphere is telltale of their relationship to 
the solar system. For the velocity of a body moving on a 
parabolic orbit with regard to the Sun, the greatest he can 
control, may be calculated, and this velocity compared with 
the observed ones. A solution of it by the writer by a 
method of interest in itself, that of a rotating field of force, 

NOTES 221 

has been published m the Astronomical Journal for April 
17, 1908, and is here reproduced. 

Consider a system of axes f , 77, f, of which f and r] rotate 
about f with a uniform angular spin n. Take the origin 
at the Sun, and let the ^ axis continually pass through the 
Earth supposed to travel in a circle. Then the space 
velocities ?/, v, and w expressed in the moving axes f, 77, 
and f respectively, or the space rates of change of f , ?;, f, 

u = f ' — nr]^ 

V =7)' + n^, 

where the accents denote the derivatives with respect to 
the time. Similarly the accelerations or the forces which 
they measure, X, V, and Z expressed in the same axes, are 







Z = 


Substituting for ^/, v, and n in the last equations their 
values from the first, we have 

Let U be the potential of the forces, 

dU TT dU ^r J dU ^ 


In the rotating field of force U is r function of f , rj, and 
^ only, since the time has been eliminated by the rotation.. 

f^= d^l di dUdri^dUd^^ 
dt d^ dt dr) dt d^ dt 

If the equations of motion be multiplied by 

d^ ^dri , d^ 

2—^, 2-— % and 2—5 

dt dt dt 

respectively, and added, they admit of an integral first 
found by Jacobi, 

>vf-n\'^=^2U-V C, 

in which v-^ = velocity of the particle relatively to the mov- 
ing axes, its relative not its space rate, 
and r= its distance from the origin reckoned by the 

We shall suppose the particle to be moving in the plane 
of the planet's motion, that of |, r}. The velocity of en- 
counter with the planet is thus made the greatest or the 
least possible, according as the particle overtakes the 
planet or meets it head on. 

Calling V the space velocity of the particle, that is the 
velocity with regard to fixed axes, and A the moment of 
momentum with regard to the same at the moment, we 

/72 _ -^^2 _|_ 2 fir cos av-^ + n^r^y 

in which a is the angle between v-^ and 7tr— hence 
r cos a =/i, the perpendicular from the origin upon the 
particle's line of motion in space, but A = v^p + nr^ by 
taking moments about the origin, of the particle's motion, 
in the rotating plane plus that of the plane itself, 

whence V^ — 2 nA = 2 U -\- C. 

NOTES 223 

We determine (7 by the consideration that for a parabola 
at infinity, 

V= and t/= 0, 

whence — since n — — — and A — ^ M + ^n- '\fly 

fi _ 

C = — 2 nA = — ^ ■ , 

where / is the parameter of the parabola and c the radius 
of the planet's orbit. 

Suppose now the particle to be just overtaking the 
planet from behind, / will very approximately be 2 r, while 

A =v^p-\-7ir'^ 

will = V— Vq'P + nr^y 

in which v^ is the velocity of the planet in its orbit, 

then v^p = nr'^ 

and A = r-V. 

2 nA =2nr ' V. 

Let M= mass of the Sun, 

m = mass of the planet, 

r= c= radius of the planet's orbit, 

p = distance from the Earth's centre to where the 

meteor enters the atmosphere, which for round numbers 
we may take at 3958.8 -h 41 miles, or 4000 miles. 
Then the attraction of the Sun on the particle is 

very approximately, 

that of the planet on the particle 




and that of the planet on the Sun whiC:h is to be applied 
reversed to bring the Sun to rest, 

This latter force acts only in the line f. 
Consequently, since X and Y are functions of ? and t) 
only, not involving /", 

U=^-^^ ^\ -—dl = Xdl, — -^7?=F^7?, 

r p r^ d^ arj 

our equation becomes 

Completing the square on the left-hand side and extract- 
ing the square root, we have 

\r p r'^ J r 

Letting M= i and r= i and determining k, the coef- 
ficient of proportionality, so that F comes out in miles per 
second, — for k enters with the masses as /^^i^ unless the 
unit of time be canonically chosen, we find, since Vq = nr, 
V— Vq = the velocity relative to the Earth 

= 10.321 miles a second when the particle 
overtakes the Earth. 

The Earth's effect in increasing the velocity which in 
this case is the greatest possible is 

28.822 — 26.163 = 2.659 miles a second. 

In the other case, when the Earth encounters the particle 
head on, v-^^ becomes negative and C negative. 

A = — v^p -{• nr'^ 
— 2nA = + 2nrV 

NOTES 225 


F2 + 



\r p 



\r p 




whence F+z'o = 45.i97 miles a second, and the effect of 
the Earth in increasing the meteor's velocity 

= 26.696 — 26.163 = 0.533 niile a second. 

The geometric explanation why the velocities cannot be 
directly added is that when each body is supposed to act 
alone the times involved in their actions are different, 
while when they act together these are naturally the same. 
In the latter case the velocity due the Sun hurries the 
particle through the space faster than the Earth's pull 
alone could, and so gives the Earth less time to act. 

Now if, instead of moving in a paraboHc or controlled 
orbit, the meteor were travelling in a hyperbolic or uncon- 
trolled one, its speed of encountering the earth would be 
greatly increased. 

But there are no instances of meteors meeting the Earth 
at speeds exceeding or even equalling 45.1 miles a second. 
From this we perceive that they are not visitants from 
outer space, travellers from other suns, but are all part 
and parcel of the Sun's retinue, kin to Jupiter and the 
Earth, the remains, indeed, of those from which the 
planets were built up. 


The Heat developed by Planetary Contraction 

To find the heat evolved by the aggregation of particles 
into a planetary mass and the subsequent shrinking of 
that mass upon itself, we first find the work done by the 
contraction and then evaluate it in terms of heat. 


Let M' — mass within a radius r ; 

then the work done by a shell dM' contracting under the 
pull of M\ the mass inside it, from infinity to the radius 
f is 

k'^M'dM' k^M'dM' 



where P is the force between unit masses at unit distance. 
If the sphere be supposed homogeneous and M be the 
mass of the nebula of radius a at any time, 

M'=M'-. dM'=sM-dr, 

or a^ 

"Jo r ^0 ^6 S a ' ^ 

the work done. 

But the sphere is really heterogeneous, and to determine 
the function of the density we proceed as follows : 

The attraction, A^ of the mass M^ upon the shell dM^ is: 



where p — the density. Let / = the pressure at the point. 
Then dp^—pAdr^ 

whence dp = - 4^^VJo P'^dr ^ ^^_ 

Now, as Laplace says, both solids and liquids resist com- 
pression more the more they are compressed. The most 
simple expression of this fact is : 

dp = Apdp, 

which is Laplace's formula. 

The Roche formula hardly gains in exactness enough to 
offset its greater complexity, as Tisserand has shown. 


Whence, substituting Laplace's value for dp above, 




Differentiating this, we have 

A. irk"^ 
The solution of this equation is, calling =;;/, 

pr = c sin mr + c^ cos mr; 

but since the density p must remain finite at the centre 

, J c sin mr . . 

where r = o, c^ = o; and p = • (2) 

To find the two unknown parameters c and m, and thus 
k, we have for the Earth, if p-^ denote the density at the sur- 
face where r—i, 

p^ = c sin m ==■ 2.74, supposed all rock, (3) 

or 2.5, allowing for the ocean; 
and also since the mean density =5.53, 

- - 4 r^ 2 ^ sin mr . , ^ 

5.53.^7r= 4^^^ dr, (4) 

3 •^o ^ 

In the determination of the work done, we must write 


c sm m- 



nc r 

Then dM^ = 4 TrrVr sin m — 

r a 

^ = 4 irac j r sin m-' dr 
Jq a 

, c^c r . r r ?-l 

= 4 TT — — s\nm m~ cos m - 

m^\_ a a a J 


r r r 

sm m m- cos m - 

whence M^ = M ^ 

sm m — m cos m 

aM' = — TT- sva m- ' dr 

sm m — wi cos m a^ a 


''k^M' dM' BM'^ 



h r (sin 7n — m cos mf 

Jr^Tm^r . o mr n^r^ . mr mr 
\ —^ sm^ — - sm — cos — 
L ^ ^ ^ ^ ^ . 

_ ;;gj;/g(f — ^wP' ni) — % sin 2;;^} >^^i^^ ^ . 
2 (sin ;;'^ — //^ cos tnf' ci 

Since the work done by a mass M in cooling / degrees is 

Majty where o- is the specific heat of the body, 

and J the mechanical equivalent of heat, 

in the case of a homogeneous body 

t = ^. for contraction from oo to the 

5 (^Ja 
radius a, 

^ k'^M a 

and therefore t = - — — (i ) for contraction from the 

5 Gja a 

radius a! to a. In the case of heterogeneity, the right- 
hand members of the equations should be multiplied by 
the ratio of (5) to (i). 

During the evolution of the heat, radiation was steadily 
draining it away, according to the fourth power of the sur- 
face temperature (Stefan's law). Convection meanwhile 
was going on from the inside out, the quantity delivered 
from one layer to the next being proportionate to their 
differences of temperature dT, while this difference was 
itself dependent on the areas involved, which were as 

-^ , and therefore their increase in the ratio -^. If we 
rr r, 



assume in consequence that the surface was never hotter 
than 10,000° F. or 5556° C, we shall have a heat sufficient 
to explain all the metamorphic and volcanic phenomena 
exhibited by geology. 

Energy let Loose during Contraction. Evaluated in Heat 

Contraction from Infinity 
TO Present State 




Contraction from JNIeteoric 
Density to Present State 

Earth 3.5 to 5.5 

Mars 3.5 to 0.71 x 5.5 

Moon 3.5 to 0.66 X 5.5 

Body supposed Homoge- 
Degrees Fahrenheit 












Body supposed Hetero- 
geneous according to 
Laplace's Assumption. 
Degrees Fahrenheit 















The Heights of Mountains on the Moon 

For simplification consider a mountain on the apparent 
lunar equator near the sunrise or sunset edge of the disk 
when the Moon shows half-full. Then, if / = the apparent 
distance its star-like summit seems off the terminator, — 
the general dividing line between sunlight and shade : 

r = the radius of the Moon ; 

we have 

h — the height of the peak ; 

/2 _|_ ^.2 = (;. + Jif, 


The lunar diameter being 2160 miles, this gives for a 
mountain four miles high an apparent isolation from the 
terminator of 93 miles, or 23 times its height. For one a 
mile high, the distance is 46 miles or 46 times its height. 
Thus the principle affords an indirect kind of magnifica- 
tion, relatively greater and greater inversely as the square 
root of the height. 

Heat acquired by the Moon 

In the expression (5) for the work done by contraction 
in the case of heterogeneity, m will vary with each planet, 
since its determination depends upon both the surface and 
the mean density of the contracting body. For the surface 
density of the Moon we have a ground surface entirely ; 
that is, one of rock. In consequence, we may perhaps 
estimate it as being that of the rocky exterior of the Earth, 
or 2.7, water being unity. The mean lunar density is 3.65. 
Putting these values in place of those of the Earth in (3) 
and (4), we get from the new (5) with the new m^ the value 
for the Moon's contracted heat given in the table. 

Since the rate of changes of the concentric shells is as 

_, while dr is taken constant, the gradient of temperature 

from the inside out will be greater, the smaller the body, 
and convection in it be more rapid. Also its surface being 
larger relatively to its volume, it would on that account 
radiate more. That surface, therefore, could never attain 
the degree of warmth of the other's in spite of the greater 
radiation at higher temperatures. We shall probably be 
within the mark if we take the surface temperature at its 
maximum as proportionate to the total heat evolved. This 
would give on the supposition of 10,000° F. for the Earth, 

NOTES 231 

400° F. Abs. for the Moon, or — 59° below the freezing-point, a 
temperature quite incompatible with volcanic phenomena. 

Surface Heat of Mars 

For Mars, where again the surface is wholly ground, 
we have pf= 2.7, while the mean density of the planet is 
3.93. With these data we obtain a new m'^ and the 
value for the heat evolved given in the table under 

Following the same course as with the Moon, we get a 
surface temperature for Mars at its maximum of 2000° F. 
This is just below the melting-point of (cast) iron, which 
is 2160° F. Such a temperature is insufficient for the dis- 
play of metamorphic or of volcanic action such as oc- 
curred on Earth. For the like reason the crumpling of 
•the crust in consequence of the planet's parting with its 
internal heat must have been much less pronounced. 


The Boiling-point of Water on Mars 

The boiling-points of liquids are functions both of the 
temperature and the pressure ; a lower temperature being 
sufficient to cause ebullition if the pressure be less. On 
the kinetic theory of gases the cause of this is at once 
comprehensible. Boiling means that the particles of the 
liquid generally have attained speed enough to throw off 
the restraint of their neighbors and leave the surface. 
Release may come about through increase of velocity, or, 
in other words, increase of temperature, since temperature 
is only another expression for the mean velocity-square 


of the particles ; or by decrease of restraint, which means 
decrease of the pressure upon them. 

Gravity on the surface of Mars is only 38 per cent of 
that at the surface of the Earth, and if the amount of 
Martian air per unit of surface be f that of the Earth, as 
later we shall see to be probable, the pressure there 
would be 

/ = M,g, = 0.09 Mg, 

where the unaccented letters refer to the Earth, the ac- 
cented to Mars. Whence the boiling-point would be 

44° C. or iii°F. 


The Paleozoic Sun 

M. Blondet's explanation of the greater warmth of 
paleozoic times was that the Sun then occupied a space 
large enough to be able to shine on the pole even in mid- 
winter. To do this, the semidiameter of the Sun must 
have subtended at the centre of the Earth an angle equal 
to the tilt of the pole away from the Sun, or an angle of 
23° 2f. This would give it a semidiameter of 37,000,000 
miles, or a milHon miles larger than the mean distance of 

Its present mean density is 1.39 times that of water. 
The density of hydrogen, the lightest known gas, is 
0.0000895 that of water at 0° C. and under a pressure of 
760 mm. at Lat. 45°. The present diameter of the Sun 
is 866,000 miles. Its density then must therefore have 

7 866000^ o 

d= 1.39. . -=0.0000178, 


or \ that of hydrogen. 

NOTES 233 

Such tenuous matter could hardly have given out any 
heat at all. This is one insuperable objection. A second 
is that to suppose that the Earth can have condensed to 
a solid state while the Sun still remained of such gaseous 
tenuity, its material more sparse than that of any known 
gas, is to violate every conception of evolution. The 
thing is mechanically impossible. 

When we reflect that so eminent a geologist as M. de 
Lapparent* espoused M. Blondet's hypothesis, we see how 
necessary to geologic conceptions is a foundation for 
them in astronomy. 


Effect on the Earth of the Supposed Paleozoic Sun 

As impossible the supposed paleozoic Sun proves from 
the point of view of the Earth. For on critical examination 
it turns out quite incapable of the climatic effect attributed 
to it, even supposing it emitted heat enough to have any 
effect at all. 

To calculate its zonal influence we proceed as follows : 
li a = coaltitude of the Sun, its insolation at the moment 
at the confines of the atmosphere is as cos a. The relative 
amount of the total insolation at a given latitude and for a 
given declination during twenty-four hours, supposing the 
Sun a point, and calling the insolation at the equator at the 
equinox unity, is expressible by spherical triangles as : 

/•cos"^(- cot b • cot c) /»cos~^^— cot b • cot c) 

I = 2 I cosa 'dA = 2 I cosbcos C'dA + sin <^sin^cos^ • dA 

/ 7 A . r ' • /f\ cos-^(-cot5- cote) 

= 2(cos COS c • A -[- Sin svci c ' s^in A) , 

where b = the colatitude of the place, 

c = the codeclination of the sun, 
A = the hour angle from noon ; 

* " Traite Elementaire de Geologic," par De Lapparent. 


the limits of the integration being the meridian, where A = o 
and the horizon where a = 90° and its cosine o, whence 

o = cos d cos ^ + sin <^ sin c cos Ay 
or A = cos"i(— cot d cot c). 

But the area of the supposed paleozoic Sun cannot be 
considered a point because of its size. To deduce its effect 
each bit of it which rises above the horizon of the place 
must be taken into account and given weight inversely as 
the square of its distance off. 

For our purpose, however, a sufficiently accurate ap- 
proximation may be got by taking in each determination 
what would be the centre of mass of the solar zone above 
the latitude of the lowest central point visible supposing 
the Sun a flat surface. The point whose codeclination is 
considered then becomes 

J'* cos 


2 r 

/'cos g 

J siii^ Ode 

where = the angle from the pole of the ecliptic toward 

its equator; 

and tan(23°.5-^) . 

"" tan23°.5 

Something is omitted by this process because the visible 
zone really descends lower at the sides than in the centre, 
but on the other hand the effect on the tropical belt of the 
Earth is relatively greater than on the polar ones because 
of the less distance of the centre of the Sun. The result 
is to understate the case against the supposed paleozoic 
Sun and thus to increase the force of the reasoning. 

From the table it appears that the climate in the polar 
regions would be unaffected in midwinter and midsummer, 
the only seasonal difference being that spring would come 



on somewhat earlier than now. Thus the seasons would 
still exist and the polar climate not be tropical at all. 

The heat due the insolation at the equator at the equinox 
is taken as unity in both cases because no greater heat 
there is to be accounted for then than now. 


Equator at Equinox = i.oo in both cases. 


Effective Declina- 
tion OF Sun 

Insolation Paleozoic 


Insolation Present 

















21. 1 




























































1. 15 




1. 15+ 












On the Influence upon the Climate of Carbon 
Dioxide in the Air 

From some careful and elaborate calculations of Profes- 
sor Arrhenius it appears that an increase of carbonic acid 
in our air to thrice its present amount would raise the tem- 
perature as follows : 

Carbonic Acid = 3 
Increase in Temperature over Carbonic Acid = i 








+ 9.1 c 

+ 9-3 C. 

+ 94 C. 

+ 94 C. 

+ 9-3 C. 


+ 9-5 

+ 94 

+ 8.6 

+ 9-2 

+ 9-2 


+ 8.7 

+ 8.3 

+ 7.5 

+ 7-9 

+ 8.1 

1 0-0 

+ 74 

+ 7.3 

+ 7-2 

+ 7-5 

+ 7-3 

We shall assume these figures to be correct and combine 
with them a table showing the present temperature at 
different latitudes in every month taken by him from 
Dr. Buchan and here abbreviated. 

Carbonic Acid = i 








-21. 1 C. 

- 8.3 c. 

+ 7.5 c. 

- 6.0 C. 

- 7-oC. 


- 1.4 

+ 7-8 

+ 18.7 

+ 9-7 

+ 8.7 


+ 17-0 

+ 21.5 

+ 26.0 

+ 23.0 

+ 21.9 

1 0-0 

+ 25.5 

+ 25.8 

+ 254 

+ 25.5 

+ 25.5 

From these two tables it appears that the increase of 
temperature from increase of carbon dioxide in the air from 



I to 3 would be only two degrees centigrade greater at 65° N. 
than at the equator ; the mean for the year at the upper 
latitude being still only + 2°. 3 C. while it would be 3 2°. 8 C. 
at latitude 5° N. In the second place the seasons in the 
polar regions would remain substantially what they are 
now. For at latitude 70°-6o° we should have : 

Temperature with Carbonic Acid = 3 






70-60 N. 

- 12.0 c. 

+ i.o C. 

+ 16.9 c. 

+ 3-4 C. 

Such cold in winter would be prohibitive to tropic vege- 
tation, and polyp corals could certainly not flourish on it 
seventeen degrees still farther north toward the pole. 

Effect of Increased Carbon Dioxide upon Plants 

Quite apart from the question of warmth it by no 
means follows that an increase of carbon dioxide in the air 
to three or four times its present amount would conduce 
to vegetation. With common plants and under otherwise 
present normal conditions it certainly does not. To de- 
termine what effect upon plants a greater percentage of 
it than the present one would have, careful experiments 
were performed in 1902 by Dr. Horace T. Brown, LL.D., 
F.R.S., and Mr. F. Escombe, B.Sc, F.L.S.* The plants 
selected were ordinary flowering plants or angiosperms. 
They found that an increase of carbonic acid in the at- 
mosphere to II. 4 parts in 10,000 from the normal amount 
of 2.8 to 3 not only hurt the growth of the plants but pre- 

♦ Proceedings of the Royal Society, 1902, Vol. LXX. 


vented reproduction. The plants became sickly and were 
unable to flower and seed. The experiment, of course, 
does not show that a different effect might not be pro- 
duced on cryptogams such as constituted the flora of Car- 
boniferous times, nor does it demonstrate that with time 
enough adaptation to such changed surroundings might 
not result in a positive gain to the plants concerned ; but it 
certainly affords no evidence in favor of either supposition. 


Atmosphere of Mars 

Amount. — Of the amount of the Martian atmosphere 
we have no certain knowledge. From its effects we know 
that such an atmosphere exists and these effects are com- 
patible with an air thinner than our own. With regard 
to its density the best determination at present is to be 
got from the planet's albedo, the albedo of a body being 
its intrinsic brightness. Now from the albedo of various 
rocks, of forests, and of snow, and from the relative 
amounts of each that appear upon the Martian disk, we 
may calculate, taken in connection with the whole albedo 
of the planet, the proportionate albedoes of its surface 
and its air. Nearly five-eighths of the surface is desert 
which has an albedo of about .16, three-eighths a blue-green 
with an albedo of .07, while less than one-sixth is of a 
glistening white of roughly .75. These would combine to 
give an albedo of .13. This, however, is illuminated by 
so much only of sunlight as penetrates the air, about three- 
quarters of the whole. Whence the apparent albedo of 
the surface seen from without must be .10. Now as the 
total albedo of the planet is .27, and .10 is from the sur- 
face, the remaining. . 1 7 must be the albedo of the air. 

Assuming the densities of the mundane and of the 
Martian atmospheres to be proportionate to their brilliancy, 

NOTES 239 

or as 75 to 17, which would seem something like the fact, 
since the denser the air the more dust it would buoy up, 
and it is chiefly by what it holds in suspension that we. see 
it, we have for the Martian air a density about two-ninths 
of our own over each square unit of surface. 

But, if the original mass of air on each planet was as 
that planet's mass, we should have for the initial amounts 
9.3 for the Earth to i.o for Mars. This would be dis- 
tributed as their respective surfaces, or in the ratio of 7919^ 
to 4220^, or as 3.5 to i ; which would give 2.7 times as 
much air for the Earth per unit of surface. The differ- 
ence between — and — , or the amount the albedo im- 
2.7 4.5 

plies now present and the amount the planet would have 
had, assuming proportionate masses to start with, may per- 
haps be attributed to the greater relative loss of air Mars 
has sustained because of parting more quickly with its air 

Surface density of its air. — To get the density of the 
Martian air at the surface of the planet, which is of course 
a very different thing from the amount of air above that 
surface, we must divide the amount by the relative gravity 
there. For the density of an atmosphere at any height 
being proportionate to its own decrease — if the density be 
taken as proportional to the pressure, which is practically 
true for gases at the atmospheric pressures considered, and 
if the temperature be considered constant — then if D 
denote the density at any point, 

dD — — Dg • dx, 
where g denotes the force of gravity at the surface of 
the Earth and is constant for the distance concerned, and 
X is reckoned outward from the surface. 

Whence D = Ae-^"^, 

A being the density at the surface. 

A «/n 


Correspondingly, we have for Mars 

A^ being the density of its air at its surface and g-^ gravity 
there. For the whole mass of air over a given point we 
have for the Earth 


and similarly for Mars 


Taking ^= i and therefore^! = .38, we have, since the 
whole mass of air above a point on Earth is 4.5 what it is 
on Mars, 

^ = 4.5^. 

Whence as ^ = 30 inches or 760 'mm. barometric pressure, 
A^— 2.5 inches, or 64 mm. 


The Mean Temperature of Mars 
Division of Radiant Energy 

So soon as a radiant ray strikes matter it suffers division 
of its energy. Part of it is reflected, part absorbed, and 
part transmitted. What is reflected is sent off again into 
space, performing no work in the way of heating the body. 
Now the amount reflected is not the same in all cases, de- 
pending for its proportion upon the character of the matter 
the ray strikes. 

If the surface of a planet be itself exposed unblanketed 
by air, the absorbed and transmitted portions go to heat 
the planet, directly or indirectly. 

NOTES 241 

If the planet be surrounded by air, the portion trans- 
mitted by this air, plus what is radiated or reflected from 
it to the solid surface, must first be considered. Then, 
upon this quota as a basis, must secondly be determined 
how much the surface in its turn reflects. The balance 
alone goes to warm the ground or ocean. 

Light and Heat 

Radiant energy is light, heat, or actinism, merely accord- 
ing to the effect we take note of. If our eyes were sensi- 
tive equally to all wave-lengths, we could gauge the amount 
of heat eceived by a body by the amount of light it re- 
flected, — that is, by its intrinsic brightness, or albedo. 
For this percentage deducted from unity would leave the 
percentage of heat received. This procedure may still be 
applied, provided account be also taken of the heat deple- 
tion suffered by the invisible rays. Two problems, then, 
confront us. 

We must find the albedoes of the several planets in 
order to compare one with another in its reception of heat, 
and we must find the relation borne by the visible and in- 
visible rays to the subject. The latter problem may best 
be attacked first. 

Actinometers and pyrheliometers are instruments for 
measuring in toto the heat received from the Sun ; and 
they have been used by VioUe, Crova, Hansky, and others 
to the determination of this quantity at given places, and 
so to a conclusion as to the amount of heat outside our air, 
or the Solar Constant. Langley's great contribution to the 
subject was the pointing out that the several wave-lengths 
of the different rays were not of homogeneous action or 
modification, and that to an exact determination of the 
Solar Constant it is necessary to consider the action of 


each separately, and then to sum them together. To this 
end he invented his spectro-bolometer. 

By means of this instrument Langley mapped the solar 
radiation to an extension of the heat spectrum unsuspected 
before. He then carried it up Mt. Whitney in California, and 
discovered two important facts : one, that the loss in the visi- 
ble part of the spectrum was much greater, not only actually, 
but relatively to the rest, than had been supposed ; and the 
other, that the greater the altitude at which the observations 
were made, the larger the value obtained for the Solar Con- 
stant. Both of these are pertinent to our present inquiry. 

With a rock-salt prism, instead of a glass one, he next 
extended still farther the limits of the heat spectrum toward 
the red, the effect of the solar radiation proving not neg- 
ligible as far as X = 1 5 /i. 

In 1 90 1 Professor Very, who had been his assistant 
earlier, published an important memoir on the Solar Con- 
stant, based upon these bolometric observations, but with 
a value for it got from spectral curves derived from simul- 
taneous actinometric and bolometric determinations at 
Camp Whitney and Lone Pine, and extended from them 
outside the atmosphere by taking both air and dust effects 
into account in selectively reflecting and diffracting the 
energy waves. The air effect is proportionate to the air 
mass, but the dust effect increases in greater ratio as one 
nears the surface of the ground. The formulae he used 
were adaptations of those by Rayleigh for accounting for 
the selective reflection and diffraction of small particles.* 

Energy of Visible and Invisible Spectrum 

Planimetrical measurement of the area enclosed by the 
curve deduced for outside our atmosphere gives the follow- 
ing results : 

* U. S. Department of Agriculture, Weather Bureau, No. 254. 


Distribution of Heat in the Spectrum 







A = 0.2 /Lt-0.393 /x 
A = 0.393 fx 

A = 0.76 fJL-I$ IX 




giving for the 

of the whole. 

Visible portion, 32 per cent, 
Invisible portion, 6d> per cent, 

Loss OF Heat in Traverse of the Air 

Turning, now, from the question of the initial heat for 
different parts of the spectrum at the time the solar radia- 
tion enters the air, we come next to consider the loss the 
several rays sustain in their traverse of it. 

From Very's curves for the radiation at the confines of 
the atmosphere at Camp Whitney and at Lone Pine, 
18 \— 1.2 /Lt, we get the amount transmitted at these two 
stations, employing planimetric measurement as before, 
and introducing with him the absorption in the red and 
infra-red from the Alleghany measures, which he considers 
the same at Lone Pine. 

From Very's measures we have, calling the whole heat 
at the confines of the atmosphere unity, — 


A=o.2 JU.-1.2 (u. 

A=i.2/x-i5 /^ 


Camp Whitney 

Lone Pine 







To get that for sea-level we shall take Crova's actinometric 
measures at Montpellier (height 40 m.), made on August 
13, 1888, at 12^30'"^, under a barometer of 761 mm. Simul- 
taneously with these, other self -registering ones were taken 
by him on Mt. Ventoux (height 2000 m.). The respective 
calories he obtained were, — 


Mt. Ventoux 

Aug. 13, I2h 30m, 1888 

0.975 calory, 
bar. 761. 1 mm. 

1.360 calories, 
bar. 613.5 mm. 

We shall reduce these to the same scale as the Lone 
Pine results, made with the pyrheliometer and used by 
Very, to wit : — 

Lone Pine 

Aug. II, 12, 14, I2h-i2h 30m, 1 88 1. 1.533 calories, bar. 663 mm. 
giving for 


1. 1 80 calories 

Mt. Ventoux 
1.643 calories 

This value of i . 1 80 is one which is probably about the 
average of clear days in our latitude, the day in question 
being registered by Crova as ''very clear." 

From these several data we find the following values 
for the solar radiation received at the respective posts, in 
calories in one column, in percentage of that entering the 
atmosphere in another. 

Solar Radiation 




Outside the atmosphere . . 

Camp Whitney 

Lone Pine 


500 mm. 
663 mm. 
761 mm. 


1. 180 

1. 000 

NOTES 245 

The loss in the visible spectrum is almost wholly from 
selective or general reflection and from diffraction, that in 
the invisible one from selective absorption. The absorp- 
tive loss by bands in the former is only about i per cent 
of the whole, and the loss by reflection in the latter prob- 
ably not over 7 per cent of its depletion. 

In view of the fact that the absorption is known to take 
place high up in the air, Very adopted the Alleghany 
amount for Lone Pine, the difference being insensible ; 
but when it comes to Camp Whitney it is clear from the 
above that 9 per cent of it is got rid of between X = 1.2 /* 
and = 10 /A by rising the 11,700 ft. from sea-level. 

Depletion in Visible Rays 

We may now find the depletion in the visible part of the 
spectrum which is not in general the same as that for the 
invisible part, decreasing relatively with the altitude and 
reversely increasing as the air envelope becomes thicker. 
It does this at a greater rate than the increase of the air 
mass, because the particles suspended in the air — dust, 
water globules, and ice — augment more rapidly than the air 
mass as one approaches the ground. 

Drawing the curve for transmission at the sea-level on 
the same principles as those for outside the atmosphere at 
Camp Whitney and at Lone Pine, and then measuring the 
amounts of transmission of each within the limits of the 
visual rays, from X = .393 /it the K line to \ = .y6 /jl 
the A band, we get the following table : — 


Transmission of Solar Radiation in the Visible Spectrum 

Calories received 


Whole Spectrum 

Visible Portion 

Outside the atmosphere 
Camp Whitney . . 
Lone Pine .... 
Sea-level .... 

The relative loss in the regions I, X = .393 /t to 

'K = .y6iJb, and II, \—.'/6/jl to X=i.2/a, betv^een the 
several stations is as follows: — 


Outside to Camp Whitney 0.105 0.029 

Camp Whitney to Lone Pine .... 0.055 o.oio 

Lone Pine to sea-level 0.086 0.027 

Light received from the Day Sky 

To these transmissions must be added that part of the 
solar radiation which is lost by reflection and diffraction 
in the atmosphere before reaching the ground, but is re- 
flected again upon it, causing the brightness of the day 
sky. This amount is sufficient to obliterate the stars. 
Compared with direct sunlight, its ratio as determined by 
Langley* is 




or 24 per cent of the sun's light. 

We must therefore increase the energy transmitted by 
24 per cent of itself. This gives finally : — 

* "Professional Papers of the Signal Service," Vol. 15. 




Portions reflected 
INTO Space 


Sea-level .... 

1. 00 



Albedo of the Earth 

Now the fraction of the incident energy in the visible 
spectrum is that by which we see the body and is called 
its albedo. The albedo of our air, then, comes out .74. 
To get the whole albedo of the Earth we must add to it 
the albedo of the surface. 

The albedo of various rocks and of the ocean is as 
follows : 


White quartzite . . 0.25 Dark slate . 

Clay shale .... 0.16 Ocean . . 

For forest we may perhaps take . 0.07 
and snow according to purity . . 0.50-0.78 

The percentages of distribution of surfaces being about 


72 per cent 
10 per cent 

Steppes and desert 
Polar caps . . . 

10 per cent 
6 per cent 

we deduce 11 for the albedo of the surface. But this 
being illuminated by only 25 per cent of the light outside 
the air gives about 3 for its quota to the planet's illumina- 
tion. When finally the Earth's whole albedo to one view- 
ing it from space becomes .74 -|- .03 = .yj albedo of the 
Earth for a clear sky. 

As the Earth's is about 50 per cent cloud-covered (see 
the researches of Teisserenc de Bort on Nebulosity) and 
the albedo of cloud is .72, we get .75 for the mean albedo 
of the Earth. 


Value of Loss of Light a Minimal One 

That the value above found for the percentage trans- 
mission of solar radiation to the Earth's surface is a maxi- 
mal rather than a minimal amount, and the albedo a 
minimal rather than a maximal one, is hinted by the fact 
that the higher the observer ascends above the surface, 
the greater his estimate of the solar constant becomes. 
Thus Langley in his memoir on the Mt. Whitney expedi- 
tion says : — 

"In accordance with the results of previous observers, 
then, and of our own with other instruments, we find a 
larger value for the Solar Constant as we deduce it from 
observations through a smaller air mass'' The itahcs are 

Depletion by Water-vapor on Mars 

We are now in position to estimate the heat actually 
received respectively at the surfaces of Mars and the 
Earth. The visual part of the spectrum containing 32 per 
cent of the incident solar radiation gives us its quota di- 
rectly from the albedo, since the heat received = i albedo. 
The infra-red portion containing 65 per cent of the whole 
depends upon the character of the air and of what it holds 
in suspension. The greater bulk of the depletion in this 
part of the spectrum comes from the absorption by water- 
vapor, water itself, or ice and carbon dioxide. At the 
Earth's surface the transmission in consequence is about 
50 per cent ; at Camp Whitney it was about 59 per cent. 
We might, therefore, suppose it still greater through the 
air of Mars, which is very thin, and if we did so we should 
find a still larger fraction of solar heat to be received by 
the planet's surface; so that such a supposition would 
actually increase the cogency of the present argument. 

* '* Researches on Solar Heat," p. 68. 



But the very thinness of the air joined to the lesser gravity 
at the surface of the planet would lower the boiling-point 
of water to something like 110° F. The sublimation at 
lower temperatures would be correspondingly increased. 
Consequently the amount of water-vapor in the Martian 
air must on that score be relatively greater than in our 

Depletion by Carbon Dioxide 

Carbon dioxide, because of its greater specific gravity, 
would also be in relatively greater amount, so far as that 
cause is considered. For the planet would part, cceteris 
paribus^ with its lighter gases the quickest. 

Whence, as regards both water-vapor and carbon 
dioxide we have reason to think them in relatively greater 
quantity than in our own air at corresponding barometric 
pressure. We may therefore assume provisionally that 
the absorption due this cause is what it is with us at 
Camp Whitney, or about 40 per cent of the whole, leaving 
60 per cent of the heat transmitted. 

It is distinctly to be noted that though this estimate 
lowers the determination of the heat received at the sur- 
face of Mars, what is thus lost in reception goes to make 
the retention of the heat received all the greater. 

Albedoes of the Planets 

The albedoes of the several planets, according to the 
latest determinations, those by M tiller at Potsdam, together 
with that found above for the Earth and that obtained for 
the Moon by Zollner, stand thus : — 


. 0.17 


. 0.92 

Earth . 

. 0.75 

Moon . 

. 0.17 

Mars . 

. 0.27 


Jupiter . . 0.75 r (using Struve's 

Saturn . . 0.88 1 latest diametral 

Uranus . . 0.73 [ measures, .78) 

Neptune . 0.63 


Heat received by Earth and Mars 
We will now apply the argument from the albedo. 

Heat received at the Surfaces of Mars and the Earth 

Per cent of 
Whole Energy 

Per cent of Heat re- 
ceived TO Whole Energy 



Visual spectrum .... 






The ultra-violet rays slightly increase the depletion by 
selective dispersion for both planets, and probably the 
more for Mars. 


But this is not all. The above deduction applies only 
to such sky as is clear. Now the Earth is cloud-covered 
to the extent of 50 per cent of its surface on the average ; 
Mars, except for about six Martian weeks, at the time of 
the melting of the polar cap and over an area extending 
some fifteen degrees from the pole, stands perpetually 
unveiled. The surface thus fog-enveloped is .034 of its 
hemisphere, and the time .23 per cent of the half year, 
whence the total ratio of cloud to clear the whole year 
through over the whole surface is less than i per cent. 

The albedo of cloud being .72, its transmission, includ- 
ing absorption re-given out, cannot exceed .28 for the visi- 
ble spectrum, and may be taken as .20 for the whole.* 
Consequently the effective heat received on this score by 

* This agrees with Arrhenius' estimate of the heat transmissibility of cloud. 

NOTES 251 

the Earth is about as .20 x .50 + i.oo x .50= .60, and for 
Mars .99, giving the ratio between the two planets that 
of .60 to .99. 

Taking now Stefan's law that the radiation of a body- 
is as the fourth power of its temperature, and remember- 
ing that, since the two planets maintain their respective 
mean annual temperatures, they must radiate as much 
heat as they receive, we have the following equation 
from which to find the mean annual temperature of Mars, 
X, in which 459.4° + 60° or 519.4° F. on the absolute 
scale denotes the mean annual temperature of the 
Earth : — 

X'. 519.4° :: ^/i^ X .64 X .99 : ■v/1.5242 x .415 x .60 

or ;r=5i9.4°f||, 

giving ;r= 531.4° Abs. =72° F. or 22° C. 

Heat received and Heat retained 

Such, then, would be the mean annual temperature of 
the planet, were the heat retained as well there as here. 
I am far from saying that such is the temperature. For 
the retention is not the same on the two planets, being, on 
account of its denser air, much better on the Earth. But 
that such is the amount received is enough to suggest 
very different ideas as to the climatic warmth from those 
hitherto entertained. 

Temperature deduced from Heat Retained 

To obtain some idea of the heat retained and of the 
temperature in consequence we may proceed in this way : 
Let y = the radiant energy received at the surface of the 


fi = that similarly received on Mars. 

e = the relative emissivity or the coefficient of radia- 
tion from the surface of the Earth, giving the 
ratio of the loss in twenty-four hours to the 
amount received in the same time, due to 
factors other than the transmissibility of the 
air, which is separately considered. 

e^ = the same coefficient for Mars. 

Clouds transmit approximately 20 per cent of the heat 
reaching them; a clear sky at sea-level, 50 per cent. 
Consequently as the sky is half the time cloudy, the mean 
transmission through its air envelope for the Earth is 

For Mars it is .60 ^j. 

To get, then, the mean temperature of the planet in 
degrees, ;r, from the heat retained, which is the daily 
mean receipt less the mean loss, we have the follow- 
ing equation, the mean temperature of the Earth being 
[519.4° F. Abs.] 288° C. above absolute zero: — 

X _ Vj/i(i — .60 e-i) 

288.5" VXi - .35 ^) 

Determination of e 

To find e we have the data that the fall in temperature 
toward morning on the Earth under a clear night sky is 
about 18° F. or 10° C. ; under a cloudy one, about 7° F. 
or 4° C. Taking the average day temperature from these 
data at 292° Abs. on the centigrade scale, or 19° C, and 
considering an average day sky and a clear night, we have 
the transmission or loss 

K-35 + -soy or .425^; 

NOTES 253 

while for an average day and a cloudy night it is 

i(.35 + .20> or .275 e. 
We form the following equation to determine e : — 

292° — 10° __ -^/(i — .425 e) 
292° - 4° " Ajy{\-.27S e) 
whence e — .47. 

Since the radiation by day is greater by about i . 1 5 than 

by night, being as ^|^, 

we have more approximately 

i-(.40+.5o>or .45 e 

for a clear night and average day and 

^(.40 + .20)^ or .30 ^ 

for a cloudy night under the same conditions. 

This gives e = .46, 

or substantially what it was before. It changes the final 
result for the mean temperature of Mars by less than two- 
tenths of a degree. 

Determination of e^ 

Since in the mean the planet radiates as much heat as it 
receives and 

^1 = 1.10, 


the radiation must be in the same ratio. Whence, the loss 
by radiation in twenty-four hours on Mars, so far as it 
depends on the heat received, is 

^1 = I.I ^ 
= .51, 


or by the more approximate calculation in the paragraph 
above, it still 

= .51. 

Substituting these values in our equation (page 250), we 
find ;r, the mean temperature of Mars, 

= 8°7C. 

or = 47°7 F., 

taking into account the heat radiated away as well as the 
heat received and gauging the temperature by the heat 
retained ; by the net, instead of the gross, amount of the 
radiant energy received. 

If we assume clouds to transmit less heat than 20 per 
cent, we diminish y and increase (i — .35^), so that the 
ultimate result is not greatly altered. 

If we take Arrhenius' formula for the temperature T of the Earth's 
surface as affected by the air-envelope, we have as determined in his 
paper on the effect of carbon dioxide in the air : — 

aA + J/+ (I - a)A(l -\- v) + n(i + -) 

7(i + v-/;^v) 
where a = atmospheric absorption for solar heat, 

/? = atmospheric absorption for earth-surface heat, 
A = Solar Constant, less loss by selective reflection by the air, 
M = heat conveyed to the air from other points, 
JV = heat conveyed to the surface from other points, 
V = I — albedo of the surface, 
y = radiation constant. 

The values for these quantities found bolometrically for a clear sky 
are a = .50, 

^ = I — .79 X .32 = .747 = whole spectrum — albedo of the air x 

visible portion, 
^ = a approximately, 
V = I — .11 = .89 

NOTES 255 

For the Earth in its entirety M ■= o and 1^=0, since what is lost by con- 
vection in one place is gained in another. 

Applying this same formula to the case of Mars, we have similarly 

a^ = .40 approximately, 

A, = (i — .17 X .32) = whole spectrum — albedo of its air x 


visible portion 
_ -946 

fi^ = ttj approximately. 

Vj = I - .13 = .87. 

Whence for the Earth under a clear sky 

J.4 _ A(i + V — va) 
y(i + V - /3v)' 

and similarly for Mars, substituting its values for A, a, and /8. 

Since in both a = fi and 7i = y approximately, we have for 7\ for Mars, 

T^ a' 

But the Earth is .50 cloud-covered, and the transmission of cloud 
being not more than .20 (the value he takes), we have finally 

T,^ ^ A, .99 
r* A .60' 

and 7" being 519.4° Abs. on the Fahrenheit, 

7; = 505.7°, that is, 46.3° F. or 8° C, 

a result substantially the same as we have deduced. 

Had we assumed /3 to be .70 and to be in like proportion to a for 

T^= 1.140^ 

and 7;* = i.ioi 



which gives not far from what we had before, since it lowers the result- 
ing temperature for Mars by only about 4° F. or 2° C. 



A Dust Storm on Mars* 

On May 25th at 15^ 34°^ G. M. T., Mr. V. M. Slipher 
noticed a large projection about halfway down the ter- 
minator of the planet. He at once notified me and we 
then proceeded to observe it by turns. 

What first impressed me was its size. This, both in 
length and height, was excessive. The projection con- 
sisted of a long band of light, a little north of the centre 
of the arc of the phase ellipse, lying parallel to the termi- 
nator but parted from it by a dark line half the band's own 
width. To this effect I made a sketch of it at 15^ 37"". 
The next thing to strike the eye was its color. This was 
not white nor whitish but ochre-orange, closely assimilated 
in tint to the subjacent parts of the disk, the region to the 
north and west of the western end of the Deuteronilus. 
Such distinctive complexion it kept throughout the time 
it was visible. Coincidentally Baltia, then close on the 
terminator and north of the projection, showed white. 
The seeing was 5 on a scale of 10 — sufficiently good to 
disclose the Phison and Euphrates double — the power 
310 and the aperture that of the 24-inch. 

As soon as possible micrometric measures were begun 
of its position and length, the position angle taken being 
that of the tangent to the terminator at the point directly 
under the projection. For such tangent, together with the 
projection's distance from the disk, furnishes all the data 
necessary to determine its location. Measures of this angle 
were repeated at intervals during the time of visibility. 

At 15*" 41™ the separation of the projection from the 
terminator seemed to have sensibly lessened and I recorded 
it in another sketch. The whole projection appeared to 

* Reprint of Lowell Observatory Bulletin, No. i, June 9, 1903. 

NOTES 257 

have moved bodily in. At 51"", however, it seemed higher 
again but then advanced rapidly toward the disk, for by 55™ 
only the tip of it could be seen. Thus it showed for some 
minutes, being last seen for certain at 16^ 8™ and vanish- 
ing completely after 16^ 10°^. 

My measures and notes were as follows, where P. A. 
denotes the position angle of the tangent to the terminator 
as above described : — 

15^ 37"^ Projection on terminator — found about five min- 
utes before by Mr. Slipher. The projection is 
long and is separated from the terminator by a 
dark line. (Drawing.) 

41 P. A. 200.°4 along terminator. 

44 Projection less separated from terminator. 

48 P. A. Projection igg^g- 

5 1 Length projection 0.^^92 ; now seems higher again. 

55 Just about gone ; only the tip showing apparently. 
No striking separation now. 

16^ 16^ P. A. Projection 199.^8; only suspected by 
glimpses ; surely seen last at 16^ 8"^. 

Impression that projection had moved toward north as 
regards Deuteronilus. 

During the course of the observation a 12-in. diaphragm 
was tried once but in this case without gain. At the same 
time Mr. Slipher's measures were these : — 

15^ 42°^ (?) P. A. Projection 203. °7. 

45 P. A. Projection 204.°o. 
Length i.'^58. 

52 P. A. Projection 20i.°o. 


Of the apparent perpendicular distance of the top of 
the projection from the terminator our respective estimates 
were : — 

By Mr. Slipher, .067 of the radius of the disk. 

By me, .075 of the radius of the disk. 

These estimates were got from measurements of our 
drawings and from remembrance of the size of the pro- 
jection as compared with the size of the disk. 

To find from these data the position of the projection 
upon the planet we may proceed as follows : We shall 
first determine the height of the highest point of the pro- 
jection above the planet's surface. 

Taking the centre of the disk for origin and the minor 
axis of the phase ellipse for the axis of x^ 
let d— perpendicular from the projection upon the ter- 
d-^ — distance to the terminator perpendicular to the 
phase axis. 
r— distance from the centre of the disk to the foot of 

the perpendicular d. 
t= distance of the projection from the centre, 
i/r = angle between r and t. 
X = exterior angle between d and r. 
A = phase latitude of the tip, or its latitude in the aux- 
iliary circle to the phase ellipse. 
<f) = angle between the tangent to the terminator under 

the projection and the major axis of the ellipse. 
a = radius of the disk, in seconds of arc. 
a^ = radius of the disk in miles. 
>^i = height of the projection in the plane of the circle 

of its phase latitude. 
/i = its true height. 

NOTES 259 ; 

f 1 = angle in the plane of the phase latitude circle be- 
tween the tip of the projection and the point on ^i 
the terminator. | 
f = same in the plane passing through the origin, the | 
observer, and the tip. -l 
6 — angle between r and the axis of x. \ 
X and y the coordinates of the foot of d. \ 
x^ andj/j those of the foot of d^. \ 
E — angle of the phase. \ 
P = position angle of the polar axis. ] 
Q — position angle of the phase equator. j 
B = latitude of the centre of the disk. 
X = longitude of the centre of the disk. 
By a property of the ellipse we have 

. /) tancf) 
tan 6> = -^, 

cos^ h . 

also r^ = 

sin^ $ + sec^ £ cos^ 
Then in the triangle made by r, d, and t we have 

/2 = ^2 _j_ ^2 _|_ 2 ^;k cos X, 

and x = ^-^y 

whence we can findj/^ d-^, and then A^ since 

sin ^ = ^ • 

Now tan f ^ = 1- 

sinE ■ a cos A ' 

and ^i=(secfi— i)(3;q • cos^, 

then since 

a^z=(a-{- Jif + h-^ — 2{a + h)k-^ cos A, 
we find h. 


Since the height of the projection is always small with 
regard to the radius of the disk, we may take 

d-i = approx., 

cos 4> 

and tan 1^ = -—, — approx., 

cos 9 sm ii • a • cos A 

and h = (sec 1^ — i)^q • cos^ A approx. 

If, as in the present case, the projection is nearly on the 
phase equator, the process admits of still greater simplifi- 
cation. For then both ^ and A become small and 

tanf= — -, approx., 


and h = (sec f — i )^o approx. 

In the present instance the height distance, from my 

estimate, is 

/?= 17 miles. 

From Mr. Slipher's, 

h= 14. miles. 

We can now find the position. Were the body causing 
the projection upon the surface of the sphere, with radius 
unity, we should have t equal to the sine of the angle from 
the centre of the disk to the tip of the projection. Since 
in reality the projection is raised above the surface, it may 
be considered to be upon the surface of another sphere 
concentric with the first and of radius a + h. The point 
directly under it will not, therefore, be where the tip ap- 
pears. But since codirectional lines from the same point, 
in this case the common centre of the two spheres, are 
altered in the ratio of their length, however projected, we 
have for the point upon the planet's surface directly under 
the projection a distance which we will call/. 

p = /. 

a-\- k 



The angle between its direction and that to the planet's 
pole, or 7, is n n fi^ ^ 

while the distance in angular measure to that pole is the 
colatitude of the centre. We thus have two sides and the 
included angle of a spherical triangle given from which to 
find the colatitude of the point or the third side and the 
lower angle or the longitude of the point from the centre 
of the disk. 

Thus calculated the positions of the projection at the 
several moments when the measures were taken prove to 
be as subjoined. 

G. M. Time 



May 26, 15'' 41"^ 
16 10 

19 44 N. 
21 24 N. 

39° 45' 

39 59 

40 33 

From the successive positions of the centre of the pro- 
jection it appears that that centre changed its place during 
the time of its visibility. It was three degrees farther 
north and three-quarters of a degree farther west at the 
end of the observations than it had been at their begin- 
ning. Such shift could be due to either of two causes. 
Bodily transference over the planet's surface would account 
for it ; or obliquity of tilt of the projection's medial line to 
the terminator would produce a like effect. To which of 
the two possible causes the result was to be attributed was 
conclusively shown by the observations of the next day. 
It is worth noticing that the shift was recorded in the 
notes as impressing itself upon the eye apart from the 
measures and confirmatory of them. 

At 15^' 51"' I measured the length of the projection 
along the terminator and found it to be o."92. If we 


allow 0/^15 for irradiation, this makes it o/'//. Now the 
diameter of the disk at the time was 10/^76 according to 
Mr. Crommelin's ephemeris which takes the value to be 
9. "30 at distance unity. Mr. Slipher's measure makes it 
greater, but as his estimates from his drawing make it 
less we may, perhaps, consider the above as a fair meas- 
ure. We have, then, for its value in degrees upon the 
planet's surface and in miles respectively : — 

Length of projection = 8.°2 = 300 miles. 

On the next evening, May 27th, the return of the pro- 
jection's longitudes off the terminator was duly awaited. 
They were due about 38"^ later than on the preceding 
night, but in order that if the projection had moved to the 
eastward in the interval it might also be caught, observa- 
tions were begun some time beforehand. My notes and 
measures read as follows : — 

1 5^^ 40™ Cannot certainly see anything on terminator, 
though I can suspect at times something at 
its centre but cannot be sure. Seeing 3. 

44^^ Suspect something just below centre of termi- 
52 Distinctly suspicious. 

58 Certainly have seen a small projection. P. A. 
I95.°8. Seeing 4. 

16 3 Thought to see it again. 

5 P. A. ig6°6, had previously thought it higher 
(up terminator). Were it anything like that 
of last night, it must certainly have been seen. 

17 Can see nothing on terminator. Seeing a good 5. 

27 Suspect projection again but cannot be sure. 
P. A. I96.°2. Have been observing about 
half the time. 

NOTES 263 

16 39 No projection visible. Seeing 3. 

40 No projection visible. Seeing 4. 

41 No projection visible. Seeing 4. 
44 No projection visible. 

At 16^^ 15™ I made a drawing of the whole planet under 
seeing as good as on the night before, using an 18-inch 
diaphragm upon the 24-inch objective, which diaphragm 
was also employed throughout the observations recorded 

Mr. Slipher, who observed with me by turns, could not 
detect any projection. 

From these observations it is at once evident that the 
something which caused the projection of May 26th, had 
ceased to exist in situ and in size on May 27th. It had 
changed its place as the position angles show, and 
had greatly diminished in extent during the twenty-four 
hours elapsed. For the position of the terminator with 
regard to the surface was substantially the same as on the 
day before. Q-P having changed in the interval only 
4-o°.i3, ^ — o.°02, and £" + 0.^29. The chief effect of 
these slight alterations of phase aspect would have been 
to delay the advent of the projection by about one minute 
of time. 

If we take now the mean of the two measures of the 
position angle at 15^ 58°^ and 16^ 5™, we find for the posi- 
tion of the tip of the projection at 16^ 3™ 

G. M. T. 



May 27, 16*^ 3™ 
and 16 27 

25° 29' N. 

25 45 N. 

3i» 43' 
36 51 

Comparing these positions with those of May 26th, we 
see that the object causing the projection shifted its place 


over the surface of the planet from 

latitude 18° 31' N., longitude 39° 45 ^ on May 26th, 

to latitude 25° 29' N., longitude 31° 43', on May 27th, 

taking the time of greatest apparition on both occasions. 
It, therefore, moved 7° in latitude to 8° in longitude in the 
twenty-four hours, or 390 miles, at the rate of sixteen miles 
an hour. From this we infer : First, that it was not a 
mountain or mountains illuminated by the sun ; and, 
second, that it was what alone fits the observations, an 
enormous cloud travelling northeast and dissipating as it 

Turning now from the observations of May 27th to those 
of May 26th, with the recognition of the rate of shift de- 
duced from this comparison of the two sets, we see that 
the change of place recorded by the first night's observa- 
tions is to be ascribed to the second of the two possible 
suppositions mentioned in their discussion, or to the form 
and orientation of the cloud. Its longer axis lay E. by S. 
and W. by N. Its axis lay, then, roughly speaking, at 
right angles to the direction of its motion. This is further 
made evident by the measures of May 27th in which the 
same tilt of the cloud's axis to the meridians is disclosed. 

We shall now see that Mr. Slipher's observations tell 
the same tale. If we deduce from his measures, as has 
been done by Mr. Lampland, the resulting positions of the 
apparent centre of the projection at different times on 
May 26th, we find as follows : — 

G. M. T. 



15^ 42™ 


14° 52' N. 
14 58 N. 
19 8 N. 

38° 2' 

36 55 
38 21 

NOTES 265 

Here again is evident a tilt of the axis of the projection 
to the meridians, such that the following end lay farther 
north and farther west than the preceding end. 

It is of interest to inquire under what conditions, diurnal 
and seasonal, the cloud came into being. As to the time 
of day, the terminator in question was the sunrise one. 
The cloud, therefore, was first seen when it was half an 
hour before sunrise upon its part of the planet, and con- 
tinued to be visible up to the rising of the sun. The place 
was within the tropics, in the desert region to the south 
of the Lacus Niliacus. With regard to the Martian season 
of the year it was, in this the northern hemisphere of the 
planet, at the time, according to the data of Crommelin's 
excellent ephemeris, what corresponds to the first of 
August with us and the sun was overhead in latitude 
18° 7' N. The cloud, then, when first seen was almost 
exactly under the sun. It then travelled north, dissipating 
as it went, and was practically dissolved again by the time 
it had reached 25° N. latitude. 

Finally, its color leads me to believe it not a cloud of 
water-vapor, but a cloud of dust. Other phenomena of the 
planet bear out this supposition. 

On May 28th no trace of it could be perceived by Mr. 

Mars on the Cause of an Ice-Age 

In a paper read some years ago before the American 
Philosophical Society * the writer showed that Mars was at 
present in the condition to offer a crucial criterion on the 
correctness of Croll's ingenious theory as to the cause of 
our own Glacial Epochs, and that the evidence presented by 
the planet on the subject did not wholly support the theory. 

* " Mars on Glacial Epochs." Proceedings Amer. Phil. Soc, Vol. XXXIX, 
No. 164. 


Croll's idea was that increased eccentricity of orbit such as 
was true of the Earth in the past brought effects in its 
train, — change of ocean currents, increased precipitation, 
and so forth, — which caused a glaciation of the hemisphere 
possessing the long cold winters and the short hot sum- 
mers. Study of Mars showed that this was putting the 
cart before the horse; that increased precipitation from 
whatever cause, and not increased eccentricity, was the 
true primiim mobile in the matter. 

The evidence offered by Mars consisted in the greatest 
and least size of its two polar caps. The minima were 
known ; of the maxima that of the northern cap had been 
determined in 1897 at the Lowell Observatory. But for 
the southern cap only seasonal comparisons with the north- 
ern at corresponding dates enabled its maximum to be 

Since then the actual maxima of the southern cap 
have been observed for the first time, and their direct data 
more than support the deductions of the previous paper. 
We may, therefore, conveniently review the subject 

The eccentricity of the Earth's orbit at present is .0168. 
In the past it has been greater, fluctuating up and down 
between values whose extreme upper limit is .0747, ac- 
cording to Leverrier's calculations. Its highest amounts 
are those invoked to account for glacial epochs. At the 
present time the orbit of Mars is possessed of an eccen- 
tricity about five and a half times our own, or .0933. It is, 
therefore, now in a more favorable condition for eccen- 
tricity to tell than our Earth ever can have been. 

The planet's axial tilt, too, upon which the differential 
action of the eccentricity in the two hemispheres depends, 
is about that of the Earth, being, according to the latest 
measures, those at Flagstaff in 1907, 23° 13' against the 
Earth's 23° 2f. 

NOTES 267 

Furthermore, these two quantities in the two orbits are 
circumstanced much the same, the Hne of apsides and that 
of the solstices faUing in both not far apart. With Mars 
the aphelion of the orbit lies in longitude 153° 19', the 
summer solstice of the northern hemisphere in longitude 
176° 48^ ; with our Earth the aphelion is in longitude 280° 
21^ the summer solstice of the northern hemisphere in 
longitude 270°. Thus both planets pass the points of 
which the near coincidence is vital to the effective working 
of the eccentricity, in fairly close succession. With Mars 
the summer solstices follow perihelion and aphelion ; with 
the Earth they precede them. This has the effect in the 
northern hemisphere of Mars of curtailing the end of sum- 
mer as compared with its beginning, and of prolonging it 
in the case of the Earth ; similarly affecting winter in the 
other hemisphere. On the other hand, in the southern 
hemisphere of Mars summer is delayed into the autumn, 
while on the Earth it is clipped. 

On Mars, then, at present eccentricity and tilt are such 
as to counterpart what the Earth has had in the past, only 
accentuated, while their positioning is not very different at 
the moment in the two. 

It becomes now of interest to note what the result of 
such increased eccentricity is on Mars. It betrays itself 
of course in the maxima and minima of the two caps. 
For a glacial epoch means that the minimum of that hemi- 
sphere's cap is a maximum. What has been learned on 
this score, then, is given in the following table : — 



north polar cap 







1886 . . . 




1888 . . . 


I28°-I72° ? 


I90I . . . 




1903 . . . 




1905 . . . 




1907 . . . 






1897 . . . 
1907 . . . 


16 days after Aut. Equi. 





1862 . . . 

1879 • • • 
1894 . . . 


Douglass and 

70 days after solstice 







1903 . . . 
1905 . . . 
1907 . . . 





NOTES 269 

Perusal of the figures proves startling to the theory that 
eccentricity of orbit is responsible for glacial epochs. For 
they show that at its minimum the southern cap, which is 
the cap of the hemisphere of extremes where glaciation 
should appear, is not only not larger than the northern but 
is actually the smaller of the two. And this in face of a 
greater precipitation in that hemisphere betrayed by the 
cap itself. For at its maximum it surpasses, as the table 
shows, the northern cap at its corresponding season. 
Eccentricity, therefore, in the case of Mars, far from caus- 
ing even a relative glacial epoch, produces exactly the 

From the respective maxima and minima of the Martian 
caps it appears that the short hot summer of the hemi- 
sphere of extremes is able to dispose of the greater deposit 
of snow of that hemisphere's long cold winter. Secondly, 
that that hemisphere's precipitation is greater than that of 
the short mild winter of the hemisphere of means; and 
thirdly, that its short summer because hot is more effective 
in melting the accumulated ice and snow than the long 
but cooler summer of its antipodes. For it reduces a 
larger maximum to start with to a smaller minimum in 
the end. 

With a certain amount of precipitation, then, to wit that 
existent at the moment on Mars, eccentricity is powerless 
to cause even an incipient glacial epoch. Suppose, now, 
the precipitation to be increased generally over the planet. 
The melting powers of the summers remain unchanged, 
approximately, except that with more deposit more fog or 
cloud would be raised which might tend to handicap the 
hotter. With precipitation equally increased the deposit 
would be more in the long cold winter in the climate of 
extremes. Its maximum would be raised and relatively 
to a greater extent than in the other hemisphere. But 
since the quantity melted in the short hot summer re- 


mained as before or even diminished, the minimum would 
be correspondingly raised until with increase of precipita- 
tion the minimum of the climate of extremes actually sur- 
passed the minimum of means and glaciation set in. 

Here, then, we see that by altering the amount of the 
precipitation, from any cause whatsoever^ an anti-glacial 
condition is changed into a glacial one. No such upsetting 
of state follows a change in the eccentricity, but merely a 
greater or less accentuation of the phenomena. Eccen- 
tricity affects the degree, precipitation the very sign of the 
resulting action. Although, therefore, both are essential 
to any distinction between the condition of the two hemi- 
spheres, it is the amount of the precipitation that really 
settles the matter. And the cause of the amount need 
have nothing to do with the eccentricity. Whatever con- 
duces to sufficient increase of precipitation will cause a 
glacial epoch irrespective of a large or a small eccentricity. 
Furthermore, as no planet at any time is without some 
eccentricity of orbit, it is precipitation that determines a 
glacial epoch or the reverse. Mars, then, throws this light 
upon the problem : it teaches us that glaciation need not 
result from eccentricity, and never will do so unaided by 
a factor which has no necessary dependence on eccen- 
tricity at all. 


Tidal Effects 

By 'unhampered age* may be denoted that placid course 
of evolution by which a planet goes to its death from in- 
trinsic cause alone. For a planet, like a man, may end its 
life for other reason than senility. Like him it is subject 
to many vicissitudes in the course of its career. One cause 
of world-extinction, perhaps the commonest of all, is the 
tidal action due the Sun. For every planet that rotates 

NOTES 271 

angularly faster or slower than it revolves is perforce sub- 
jected to enormous partitive strains. Since its body is not 
absolutely rigid these strains become tides, superficial or 
bodily, which act as brakes to bring the rotation and the 
revolution to coincide. Eventually such synchronousness 
must result ; it is only a question of time. When it befalls 
the planet that body ever after turns in perpetuity the 
same face to the Sun. This fate has already befallen 
Mercur}^ and Venus, and must in time overtake the rest. 
One side of the planet is thenceforward forever baked ; 
the other forever frozen. Whatever water originally ex- 
isted there will have circulated, caught up by the heated 
currents of the sunward side, to the hemisphere that is 
turned away, there to be deposited as ice. This alone 
would terminate all possibility of life, and the planet roll 
a mummified mass through space. 


On the Visibility of Fine Lines 

The minimtim visibile of the normal human eye is com- 
monly taken at i' of arc. In other words, the separating 
power of the eye by which two objects may be distin- 
guished as distinct has this for its minimum distance of 
effectibility. The limit is not, however, the same for all 
eyes, varying from individual to individual, and depends 
upon what is known to oculists as acuteness of vision. It 
is something quite apart from near-sight or far-sight and 
resides apparently in the fineness of the retinal rods, some 
eyes having these much coarser than others. Nor is it the 
same thing as sensitiveness to impression, though the one 
ability is often taken erroneously as guarantee for the 
other. Eyes, however, have two quite distinct capabilities, 
sensitiveness or the power of distinguishing faint contrasts 


such as detecting faint stars, and acuteness or the power 
of resolution of parts to which is due the detection of plan- 
etary detail. The existence of the one faculty does not in 
the least vouch for the presence of the other. Indeed, 
experience with many observers has shown me that the 
two are rarely, if ever, found in a high degree together. 

Although points may not be distinguished as a rule if 
they lie closer together than i^ of arc, it is an interesting 
and, at first, curious fact that a line, having a breadth 
much less than the minimum visibile and much less even 
than what would enable it to be seen were it a point, can 
be distinctly and easily perceived. Michelson has shown 
theoretically that this must be so, and has further experi- 
mented practically to the same conclusion. Before know- 
ing of Michelson's work some experiments of my own had 
shown me that such was the case, as indeed every one un- 
consciously evidences when he sees a spider-web. My 
first experiments sufficed to show me a line whose breadth 
was less than 2. ''6 of arc. It was a telegraph wire, seen 
against the sky, whose distance away was then measured. 
Recently I repeated the experiment with more care and 
with the results which follow. 

On May 6 of this year a wire was stretched by Mr. 
Lampland and the writer from the top of the dome to the 
top of the anemometer stand near it in such a manner that 
it could be seen against the sky down a vista of half a 
mile to the west. The wire was an iron wire of the usual 
kind, .0726 inch in diameter, brownish and somewhat 
rusty. In color, therefore, it was not very dark. We be- 
gan to observe it from a distance of 500 feet, at which it 
was instantly unmistakable, up to 2100 feet, where it wholly 
ceased to be visible. The distances at which it became 
less and less perceptible, the character of that perception, 
and the angular width of the wire at the several distances 
are given in the subjoined table. The remarks are mine, 



from my observations, but they were almost exactly con- 
curred in by Mr. Lampland. 

Visibility of a Wire .0726 Inch in Diameter 




500 feet 


Evident at first glance. 

600 feet 

2. "08 

Evident at first glance. 

700 feet 

I. "78 

Evident at first glance. 

800 feet 


Evident at first glance. 

900 feet 


Evident at first glance. 

1000 feet 

I. -25 

Easily evident. 

II 00 feet 

I. "13 

Perfectly visible. 

1200 feet 


Distinctly visible. 

1300 feet 


Visible but not easy. 

1400 feet 


Visible but not difficult. 

1500 feet 


Visible but difficult. 

1600 feet 


Glimpses only. 

1700 feet 


f Well glimpsed. Imaginary wires glimpsed 
[ but not surely. 

1800 feet 


f Well glimpsed. Imaginary wires glimpsed 
1 but not surely. 

1900 feet 


Glimpses not sure. 

2000 feet 


It and imaginary lines of equal impression. 

2100 feet 


Not visible. 

It is interesting to note the fact that at a certain stage 
of difficulty in detection, imaginary wires or impressions 
of wires which did not exist were reported by the eyes or 
the optic lobes to the brain and that such could be distin- 
guished from the true, not, be it understood, from their 
position, but from direct subconsciousness of the impres- 
sions they made. The sight of a wire carried with it at 
once a sense either of certainty or of doubt, and this as 
the table shows was a concomitant of the strength of the 
impression. Up to 1800 feet the eye or brain could dis- 


tinguish of itself, apart from position, the reality or ques- 
tionableness of the impression. At 1900 feet and still 
more at 2000 feet consciousness was unable to part the 
false from the true. 

To apply this now to those tenuous lines upon the sur- 
face of Mars known as the " canals " of the planet. It 
may be well to say in premise that, when seen under good 
conditions of air and observer, they are not bands or 
washes or separating shades, but perfectly definite lines 
which range all the way from such as might be made by 
a pen and india-ink to gossamers like spider-webs seen to 
the naked eye. As a mean case of distance we may take 
the planet to subtend in diameter an arc of 14". Suppose 
also that a power of 310 be used, which is also a mean 
power. If the telescope lost no light and the definition 
through it were as good as to the naked eye, it should be 
possible to observe a line on the planet whose width was 

o "6q I 

• ,/ X of the planet's diameter. 

• 14/^0 310 

Now the planet's diameter in miles is 4220 ±. In miles 
then the width would be 

o."6q I 

4220 X 77^ X , 

14. 'o 310 

or If of a mile. Say f of a mile. 

Were the planet at a near opposition when its apparent 
diameter is over 24'' and a power of 450 were used, we 
should have about one-quarter of this for the width which 
might be seen, or 

-^Q of a mile. 

As the telescope does lose both in light and in definition 
over the naked eye, it would not be possible to reach this 
limit. If, however, we suppose the naked eye to be three 
times as effective, it would seem not to favor the telescope. 

NOTES 275 

At this estimate J mile would be the limiting perceptible 

Why a line can be seen when its width is but -^^ of the 
minimum visibile seems to be due to summation of sensa- 
tions. What would be far too minute an effect upon any- 
one retinal rod to produce an impression becomes quite 
recognizable in consciousness when many in a row are sim- 
ilarly excited. Psychologically it is of interest to note that 
there are stimuli perceptible so faint and so fleeting as to 
be even below this limit, and that, unable to rise into direct 
consciousness, leave only an indefinite subconsciousness 
of their presence which the brain is unable to part from 
its own internal reverberations. It is a narrow limbo, this 
twilight of doubt, since, as we see in the present instance, 
below o."59 the object produced no effect, and above o.'''69 
the brain was cognizant of objectivity as such. 

Notes on Visual Experiment 

The following visual experiment was performed at the 
request of Director Lowell, and the notes may be con- 
sidered as supplementary to those of the experiment on 
the visibility of a wire * — the experiments being identical, 
except that in the last instance a disk, having a fine line 
of same width as wire ruled across its face, was observed 
along with the wire. 

As a check against any influence that a knowledge of 
the positions of the wire and line might introduce, the ob- 
server V. M. S. had nothing to do with the preparation and 
arrangement of the experiment, and made his observations 
going toward the disk and wire, the observations being 
begun at the extreme limit of visibility for the Hne and 

* Lowell Observatory, Bulletin No. 2. 


For each series the results are practically the same for 
the two observers — the one having no knowledge as to 
the positions of the objects and making his observations 
going towards them, the other beginning observations near 
the objects and going away from them. 

V. M. Slipher. 
C. O. Lampland. 
December, 1903. 

Wooden disk eight feet in diameter, covered with white 
paper, with fine blue line, .07 inch wide, ruled across its 
face. Line on disk makes about same angle with hori- 
zontal as wire stretched above it. Disk suspended from 
cable, stretched from top of dome to a pine to the south- 
west. Plane of disk nearly in the meridian. Wire same 
width (.07 in.) and color as that used in the original ex- 
periment. (Lowell Observatory Bulletin No. 2.) 


100 ft. Wire and lines on disk very distinct. — c. O. L. 
Angular width : disk, 4° 35' ; lines, I2."48. 

200 ft. Line stronger than wire. — v. m. s. 

About the same as the 100 ft. station. — c. O. L. 

Angular width : disk, 2° ly/^ ; lines, 6."24. 
300 ft. Line stronger than wire. — v. m. s. 

Both wire and line on disk strong and well seen. Perhaps 
line the stronger. — c. o. l. 

Angular width : disk, 1° 3i.'7 ; lines, 4." 16. 
400 ft. Line the stronger. Probably due to background offering 
greater contrast. — v. m. s. 

About as well seen and as evident as at 300 ft. station. — c. O. l. 

Angular width : disk, 1° 8/8 ; Hnes, 3. "12. 
500 ft. Wire and line equally sharp and evident. — v. M. s. 

Wire and line evident and distinct at first glance. — c. O. l. 

Angular width : disk, 55' ; lines, 2.^50. 
600 ft. Disk in shadow, yet line well seen, as is also wire. Line more 
permanently visible, perhaps. — v. m. s. 

NOTES 277 

Line on disk distinct and evident, but becoming more difficult. 
Illumination very bright and glaring. Wire distinct and 
evident first glance. — c. o. l. 
Angular width : disk, 45. '8 ; lines, 2. "08. 
700 ft. Inaccessible. — v. m. s. 

Poor station for observation. — c. o. L. 
Angular width : disk, 39.^3 ; lines, i. "78. 
800 ft. Inaccessible. — v. m. s. 

Wire comes out very distinctly — stronger at times. Line on 
disk becoming more difficult — somewhat difficult at times 
from this station, but perfectly evident with good illumina- 
tion. — c. o. L. 
Angular width : disk, 34.'4; lines, i."56. 
900 ft. Can see wire. Disk in shadow of tree. — v. M. s. 

Angular width : disk, 30.'6; lines, i. "39. 
1000 ft. Wire more difficult but perfectly evident. Line on disk also 
becoming difficult, but glimpse it definitely with good illumi- 
nation. — c. o. L. 
Angular width : disk, 27.^5 ; lines, i."25. 
1 100 ft. Can see wire and line. Shadow is on disk. — v. m. s. 

Both wire and line on disk perfectly and distinctly seen. — 

C. O. L. 

Angular width : disk, 25' ; lines, i."i4. 
1200 ft. Certainly glimpse line; poor glimpses of wire. — v. m. s. 

Wire rather difficult and at times not seen, but glimpsed per- 
fectly at intervals. Line on disk glimpsed distinctly at 
times when angle of illumination changes. — c. o. l. 

Angular width : disk, 22.^9; lines, i."o4. 
1300 ft. Certainly ghmpse line and wire. — v. m. s. 

Wire difficult now, but glimpsed at times. Line on disk fairly 
well glimpsed as wind swings disk, but becoming difficult — 
somewhat faint. — c. o. l. 

Angular width : disk, 21. '2 ; lines, 0.^96. 
1400 ft. Do not glimpse either wire or line. Hasty observations. — 
V. M. s. 

Line on disk glimpsed at times as disk swings, but faint, diffiise, 
and difficult. Wire glimpsed but difficult. — c. o. l. 

Angular width : disk, 19. '6 ; lines, o."89. 
1450 ft. Certainly glimpsed wire. Cannot certainly glimpse line. I 
get glimpses of a fictitious as well as what I take to be a 
real line. It is (if glimpsed) illy defined. — v. m. s. 

Angular width : disk, 19' ; lines, o."86. 


1500 ft. Wire at this station extremely difficult. Not certain that I 
glimpse it. Line on disk seen at times, but now faint and 
diffuse. Shadow of tree on part of disk. — c. o. l. 
Angular width : disk, 18. '3 ; lines, o."83. 

1600 ft. Wire not certainly glimpsed : imaginary wires seem about 
equally strong. Shadow of tree on disk, obscuring line. — 

C. O. L. 

Angular width : disk, 17. '2 ; lines, o."78. 


Same disk, and wire for comparison, as used in the first 
series of these observations. 

100 ft. Wire and line on disk very distinct and clear cut. — c. o. L. 
200 ft. 300 ft. station remarks hold. — v. m. s. (Observations made 
going towards wire and disk.) 
About the same as at 100 ft. station. Line the stronger. — 
c. o. L. 
300 ft. 400 ft. station remarks hold. — v. m. s. 

Well defined at first glance — both wire and line on disk, line 
perhaps the stronger. — c. o. l. 
400 ft. Line easier than wire and more definite. (Due to back- 
grounds ?) — V. M. s. 
Distinct and well seen at first glance. (Line appears the 
stronger). — c. o. l. 
500 ft. Line more definite than wire. (Some telephone wires pass 
before the disk ; these are easier and more definite than 
wire.) — V. m. s. 
Distinct and well seen at first glance. No appreciable difference 
from 400 ft. station. — c. o. L. 
600 ft. Line easier than wire, except where the latter crosses cables. 
(Cables from which disk is suspended.) — v. m. s. 
Wire and line on disk seen with perfect ease and distinctly, 
but fainter than at 500 ft. station — seen at first glance. — 

C. O. L. 

700 ft. Line easier than wire. — v. m. s. • 

800 ft. Disk inaccessible. Wire seen. — v. m. s. 

Poor station. Trees interfere with observations. — C. O. l. 
900 ft. Wire and line only fairly seen. — v. m. s. 

Wire quite well seen but somewhat faint and diffuse. Line on 
disk glimpsed at times but difficult. Disk very bright — 

NOTES 279 

illumination not the best for seeing line. Later : Line seen 
quite well when the disk was swung by the wind. Faint. — 
c. o. L. 

1000 ft. Inaccessible. — v. m. s. 

Wire glimpsed at instants. Disk obscured by trees. — c. o. L. 

1 100 ft. Line well glimpsed : wire doubtfully. — v. m. s. 

Wire glimpsed, but faint and diffuse and not visible all the 
time. Line on disk distinctly seen when disk swings around 
for favorable illumination. — c. o. l. 

1200 ft. Glimpse wire rather doubtful. Line and wire glimpsed some- 
what more certainly than at 1300 ft. station. — v. M. s. 
Wire very difficult — ghmpsed but faint and diffuse. Line on 
disk glimpsed but faint. — c. o. l. 

1300 ft. See some markings on disk as before, i.e.^ in second and fourth 
quadrant. Perhaps glimpse wire. Line more definitely 
glimpsed. — v. m. s. 
Wire very difficult — glimpsed at intervals — diffiase and some- 
what uncertain. Line on disk also very difficult most of the 
time ; very faint and diffuse. As disk swings from wind it 
is distinctly glimpsed at times. — c. o. l. 

1400 ft. Glimpse line and have occasional glimpses of fictitious markings 
(on disk). I once imagined I ghmpsed wire. There is a 
dark spot in second quadrant, and glimpse line from 0° to 
290°. — V. M. s. 
Cannot certainly say that I glimpse ware — now of about same 
strength as imaginary wires. Line on disk fairly well 
ghmpsed at times, as disk swings, but faint and diffuse. — 

C. O. L. 

1500 ft. Cannot see wire. Suspect it and line on disk at times, but 
uncertain. — c. o. l. 


Canals of Mars 

At the opposition of 1907, 264 canals were seen and 
drawn by the writer ; a large number also by Mr. C. O. 
Lamp land ; and many, including some new ones, by Mr. 
E. C. Slipher in South America, not yet catalogued and 


Of the 264 canals mapped, 85 were new. Owing to the 
tilt of the axis and to the Martian season of the year, these 
were mostly not only in the southern hemisphere but in the 
more southern part of it. The position of the new canals 
was as follows : — 

i) 32 in the light regions. 

2) 34 in the dark regions or in those of intermediate tints. 

3) 12 in or through the southern 'islands.' 

4) _2 at the edges of dark regions. 

85 in all. 

Added to those already recorded these make : — 

336 + 32 = 368 in the light regions. (i 

lOi + 53 = 154 in the dark ones. (2, 3, 4 

522 in all. 

Of the canals seen 28 were double or about ^ of the whole 
number showing. Those not hitherto so seen were the 

Cyclops II 

Cambyses (?) 



making 56 doubles in all. 


Position of the Axis of Mars 


The position of the pole of Mars, determined by Lowell 
in 1905 from a synthesis of his own observations on the 
polar caps and of previous ones of the same, was : — 

R.A. 3i7.°5 Dec. 54.°5 

NOTES 281 

This gave for the tilt of the Martian equator to the Martian 

23° 59^ 

This position of the axis of Mars was adopted by the British 
Nautical Almanac. The same is to be incorporated in the 
American Ephemeris. 

In 1907 two very full series of observations on the south 
cap were obtained at Flagstaff which confirmed the several 
previous series taken there, suggesting that still greater 
weight should be given them in the synthesis than had 
previously been assigned. The resulting inclination of the 
Martian equator upon the Martian echptic is 

23° I3^ 


Aeria, 209. 
Air, 12. 

thinning of, no bar to a species, 96, 


on mountain tops, 98. 

of Mars, 139, 186. 

density at Martian surface, Notes 

of Mars, 78, 84. 

of Venus, 78. 

of each planet, 84, Notes 249. 

of Earth, Notes 247. 
Amphibia, 53. 
Animal life, 

on peaks, 103. 

dependent on temperature, 103. 
Antarctic zones, 183. 
Aqueducts of Carthage, 128. 
Arabia, 125. 

Arctic zones of Mars, 183. 
Areolas of Mars, 151. 
Arequipa, 153. 
Arethusa Lucus, 196. 

of Martian markings, 195. 

of canals, 211. 
Ascraeus Lucus, 157. 
Asia, deserts of, 125. 

later found less evident than earlier, 


gravitational, i. 

physical, i. 

of Mars, 77, Notes 238. 

shown by cloud, 78. 

evidence from albedo, 78. 

proved by limbiight, 79. 

by changes in surface features, 80, 

polar caps first to betray, 80. 

circulation of, 130. 

amount of, Notes 238. 

Axial tilt, 

of Earth, 71, Notes 266. 

of Mars, 77, Notes 266. 
Axis of Mars, Notes 280. 

Beer, 81. 

Blondet, M., 48, Notes 232, 

Blue band, 

surrounding polar caps of Mars, 81-82. 
Blue-green areas of Mars, 104-106, 133, 


use in surface temperature deter- 
mination, 85. 
Boltzmann, 86. 

Casnozoic time, 45. 
Cambrian era, 45. 
Campbell, 138. 

discovery of, 146. 

geometric look of, 147. 

as straight lines, 148. 

breadth, of, 149, 160. 

length of, 149. 

in dark regions, 152-153. 

rendezvous at special points, 152. 

photographed, 154. 

superposed over main features, 155. 

double, 159-167, 190. 

direction of, 164-165. 

subject to change, 167. 

research, new method of, 168. 

career of, 171. 

cartouches of, 172-175, Notes 249. 

quickening according to latitude, 175. 

quickening starts at polar caps, 176. 

vegetation explains behavior, 177. 

advent of water down the, 181. 

not cracks, 191. 

not rivers, 191. 

nerve and body, 210. 

artificiality, 211. 

number of. Notes 279-280. 




Carbon dioxide, 

amount in atmosphere in paleozoic 
times, 51. 

a bar to the passage of heat, 51. 

on Mars, 104, 107. 

influence on climate. Notes 236-237. 

effect of, on planets. Notes 237. 
Carboniferous periods, 45, 53. 

heat of, 47-48. 

little light in, 47-48. 
Carets of Mars, 212. 

aqueducts of, 128. 

desert character now, 129. 
Cartouches, of canals, 172-175, Notes 

Casius, wedge of, 133. 
Ceraunius, 173, 176. 
Chagos Archipelago, 121. 

tree trunks changed to, 127. 
Challenger expedition, 42, 59, 62-63. 

bathymetric, 2)Z- 
Chemical affinity, 

relation to plants, 36. 

relation to stones, 37. 

life a manifestation of, 37. 

on Mars, 22, 52, 77-78, 85-86. 

on Earth, 85. 
Conifers, 70. 
Continents of Mars, 146. 
Coral reefs, 

found only in warm seas, 46. 

in past ages, 71. 
Cowper, 17. 

Cretaceous period, 64, 71. 
Croll, 1 1 2-1 13, Notes 265. 
Crommelin, Notes 262. 
Crova, Notes 244. 
Crusts of planet, 

formed over molten mass, 13-14. 

crinkling of, result of cooling, 14-15. 

crinkling of, where most pronounced, 

knowledge of, derived from Earth, 

Moon, Mars, 14, 16. 
Crustacea, 60. 
Cryptogams, 47, 70. 
Cycads, 70-71. 

Dana, Professor, 119. 
Darwin, Sir George, 26. 


length of Martian, 77. 
Dead stage, 

of planetary career, 12. 

Moon and larger satellites in, 12. 

Laplacian law of, 24. 

meteoric, 28. 

of the Earth, 14. 

of the Earth's surface rocks, 14. 

girdling Earth, 124, 129. 

on Mars, 131. 

on Earth, 124. 

on Mars, 134. 
Devonian era, 

plants found in, 46. 
Djihoun, 161, 203. 
Douglass, A. E., 153, 200. 
Dust storms on Mars, 22, 89, Notes 

Earth, planetary career of, 13. 

of Earth's orbit. Notes 266. 

of Mars' orbit. Notes 266. 

existing if water be present, 39-40. 
Elysium, 160. 
Eocene period, 72. 
Eumenides-Orcus, 149, 151, 156. 
Euphrates, 213, Notes 256. 

gain of land in, 120. 

planetary, i, 3-34. 

of life, 35-69. 

Earth not Sun the motive force of, 
52, 72. 

effect of environment upon, 54. 

general principle of, 69. 

steps of, 1 08- 1 10. 

of Earth and Mars, 73, 186. 

Fal, 57. 
Fauna, 45, 58. 

evidencing planetologic eras, 


Galitzine, 86. 
Ganges, 205. 
Gardiner, Stanley, 121. 




Generation, spontaneous, 37, 67. 
Geology, a part of planetology, 13. 

Mars not suffering from wholesale, 89. 
Gravity, on Mars, 210, Notes 232. 
Gymnosperms, 70. 

Habitability of Mars, 96-97. 
Habitat, of animals, 129. 

of Mars, 215. 

destined to pass away, 216. 
Haeckel, 39. 

substances vary with, 8. 

radiation of, in planetary evolution, 
9-10, 25. 

of paleozoic times excessive, 48-51. 

acquired by the Moon, Notes 230. 

of Martian surface. Notes 231. 

received by Earth and Mars, Notes 

retained by Earth and Mars, Notes 

Heat of condensation, 

dependent on mass, 7-8, 23. 

for homogeneous body, 7-8, 24, 

for heterogeneous body, 8, 24. 

evaluated for Earth and Moon sup- 
posing origin the same, 24-25. 

compared for Earth and Mars, 27. 

developed by planetary contraction. 
Notes 225-229. 
Hibernation, 90, 96. 

snow line and timber line on, 99. 
Huygens, i, 138. 

Icarii Luci, 212. 

Mars on the cause of, Notes 265. 
Illumination, slant, 17. 

heights of mountains measured by, 18. 
Indo-Pacific, coral-reef region, 121. 
Isoflors in Arizona, 100. 

Janssen, 138. 
Jurassic period, 71. 

Lampland, C. O., 154-155, Notes 264, 

272, 276-279. 
Landscape, the result of cooling, 14. 
Langley, 85, 88, Notes 241. 
Laplace, i, 24. 

Lapparent, de, 48, 68, Notes 233. 

origin of, 35. 

an inevitable phase of planetary 
evolution, 37, 66. 

a manifestation of chemical affinity, 

37, 38. 

water essential to, 39. 

outgrows the sea, 53, 55, 68. 

adaptability of, 56, 96, 97. 

deep-sea, 57-64. 

cosmic character of, 64. 

did not reach Earth from without, 66. 

the outcome of planetary cooling, 66. 

mode of manifestation, 107. 

types of, 142. 

chemical constituents of, 179. 

proves existence of atmosphere on 
Mars, 79. 
Little Colorado, 127. 
London, size of, 214. 
Lower Silurian era, 

wings of insects found in, 46. 
Lucus Phoenicis, 161. 

Madler, 81. 

Man, first appearance of, 68. 

Mare Acidalium, 133. 

Mare Icarium, 158. 

Mass, 15, 16, 31, 39. 

the fundamental factor of planetary 
evolution, 9. 

comparative, of Earth, Moon, Mars, 
Maxwell, Clerk, 139. 
May-flies, of Carboniferous era, 47. 
Mercury, markings of, 192-193. 

rotary retardation of, 207. 
Merriam, Dr., 90, 95, 99. 
Mesozoic time, 45, 71. 
Metamorphic rocks, 12. 

age of, 12. 

akin to furnace slag, 13, 14. 
Meteoric swarms, 

gravitational heat of, 7, 8, 67. 
Meteorites, 4, 34. 

constitution of, 4, 6. 

size of, 4. 

velocity of, 4, 5, Notes 220-225. 

fused by friction with atmosphere, 4. 

worship of, 4, 5. 

relation to solar system, 4-6. 

oldest bits of matter, 5. 



Meteorites — Continued. 

occluded gases in, 6. 

density of, 28. 

members of solar system. Notes 225. 
Michelson, Notes 272. 

beings revealed by, no. 

evidence of, 143-144. 

effect on planetary markings, 215. 
Miocene period, 68, 72. 

edible plants and plant eaters in, 68. 
MolecTole, organic, 35-36. 

six elements of the, 37-38. 

relation of atoms to, producing vital 
actions, 37. 
Molten stage, 12. 

Neptune, Uranus, Saturn, and Jupiter 
in, 12. 
Moment of momentum, 

of solar system, 3, Notes 219. 

of Alpha Centauri, Notes 220. 

proportional to mass of planet, 15. 

none on Mars, 16, 19, 20-22. 

heights measured by slant illumina- 
tion, 18. 

on Moon, 19, 23, 27, Notes 229-230. 
Mt. Whitney, 

bolometer investigations at, Notes 
Miiller, 84. 

Newton, i. 

Nilokeras, 161. 

Nitrogen, on Mars, 104, 107. 

connection with life, 179. 
North America, gain of land in, 119. 

an analogue of prehistoric cataclysms, 


first seen, 157. 

form, demonstration of function, 157, 


shape of, 197. 

behavior of, 197. 

probable meaning of, 213-214. 
Oblateness of Mars, 199. 
ObHquity of Martian ecliptic. Notes 281 . 
Oceans, 12. 

origin of, 28. 

distribution of, on Earth and Mars, 

Oceans, relative size on different 
planets, 30-32. 

Moon more profusely endowed with, 

basins of, unchanged, 32-34. 

basins of, on Mars, 132. 

character of bottoms of, 33, 34. 

cooling of, occasioned development of 
higher forms of life, 43. 

of Earth, disappearing, 118. 

on Earth, 141. 

absent on Mars, 112, 187. 
Oligocene period, 72. 

eccentricity of Earth's, Notes 266. 

eccentricity of Mars', Notes 266. 

evolution of, 205. 
Origin of Moon, 25. 

Darwinian theory of, 26. 

explained by heat investigation, 25-27. 

the chief factor in all organisms, 38. 

one-half the substance of the Earth's 
svirface, 38. 

on Mars, 104, 107, 137. 

connection with life, 179. 

Paleozoic time, 45. 

light less and heat more than now, 

48, 51- 
light and heat of, not explained by 

Sun, 49-50. 
Earth itself responsible for heat of, 

50, 52. 
Palestine, 129. 
Permean period, 54. 
Petrified forests of Arizona, 125, 126. 
Phison, 158, 213, Notes 256, 
Phoenix Lake, 149. 
Pickering, W. H., 153, 157. 
Pigments, put on by the Sun, 72. 
life history of, dependent on size, 11. 
internal heat of, its initial motive 

power, 13. 
cooling the mode by which its energy 
worked, 9-10, 13, 28. 

the connecting link between nebular 
hypotheses and the Darwinian 
theory, 2. 
six eras of, 11 -12. 
geologic part of, 13-14. 



Plant life. 

Carboniferous, 46-48, 51. 

light a necessity to, 58. 

not existent in deep seas, 63. 

entrance of plant eaters with, 68. 

temperature of, as compared with 
peaks, 99. 

Pliocene period, 72. 
Polar caps, 

of Mars, 80, 204. 

constitution of, 81-82. 

not solid carbonic acid, 81-82. 

of Earth, ourselves dwellers in, 90. 

diminish, 114. 

snows of, 180. 

canals from, 197. 

water of, 204. 

Notes, 268. 
Partus Sigaeus, 158. 

of snow. Notes 269-280. 

substances vary with, 8. 

on Martian terminator, 20. 

not indicative of mountains, 21. 

due to dust clouds, 22. 
Propontis, 133. 
Protonilus, 158. 

first possible with formation of water, 

nine-tenths water, 41. 

first existed in water at a high tem- 
perature, 42. 

formed, the moment cooling per- 
mitted, 67. 
Psehoas Lucus, 158. 

Radiant energy, 

reflection of, from atmosphere and 
surface of planet, 83-84. 

on Earth, 130. 
Reptiles, advent of, 54. 
Rills, of the Moon, 191. 
Rotation of Mars, 75-76. 

relative, of Earth, Moon, Mars, 16. 

exception to theoretic order, 27,. 

Sabaeus Sinus, 212. 
Sahara, the, 125. 

San Francisco Peaks, 90, 127. 

zones of vegetation on, 93-94. 

animal life on, 95-97. 

life on, 103. 
Sarasin, 57. 
Schiaparelli, 104, 146, 147, 151, 152, 


on Earth, 118. 

on Mars, 118. 
Sea-level, lowering of, 121. 

the earliest home of mundane life, 
41-42, 68. 

sedimentary formations dependent on, 


inland, 121. 

drying up of, 123, 

absence of, when Earth was screened 
from Sun, 51. 

advent registered in changed vegeta- 
tion, 71-72. 

long on Mars, 78. 

two, of Martian growth, 183. 

relative length of, determined, 113. 
Seaweeds, 45. 
Sedimentary formations, 

fourth evolutionary stage, 12, 43. 

dependent on seas, 43, 44. 
Sihcon, 38. 
Silurian era, 45. 

Sky, light of, by day, Notes 246. 
Sladen expedition, 121. 
Slipher, E. C, Notes 279. 
SHpher, V. M., 138, Notes 256, 276. 
Slope exposure, 102. 

of polar caps, 180. 

precipitation of, Notes 269-270. 

in Alaska, 141. 

on Mars, 141. 
Solar constant. Notes 242. 
Solar system, 

catastrophic origin of, 3. 

moment of momentum of, 3, Notes 219. 

meteoric constitution of, 5. 

meteorites, members of. Notes 225. 

supplanting of others by one, 206. 

unification of, 207. 
Spectroscope, the, 137. 
Spectrum, energy of, Notes 242. 



Stefan, 86. 

Struggle for existence, 204-205. 

Struve, Hermann, 200. 


the life season, 90, 95, 96. 

investigation on, by Dr. Merriam, 
90-91, 95. 

bearing upon the habitability of Mars, 

paleozoic, 49, Notes 232-235. 

causes seasons, 50. 

not the soiurce of Earth's early heat, 


becomes dominant, 70. 

first let in by Earth's cooling, 70. 
Sxm stage, the, 12. 
Surface features of Mars visible, 73. 

permanent in place, 77. 

changes in, 80. 

smoother than Earth's, 186-187. 
Surface heat, 

of Moon, 87, 88. 

of Mars, 89. 

their air compatible with great, 87. 
Surface of equilibrium, 201. 

Teisserenc de Bort, Notes 247. 
Telluric lines in spectrum, 137. 

of Mars, 89. 

due to the Sun, 83. 

new determination of, 83-86. 

in summer and winter, 87. 

mean, Notes 240-255. 

within which life can exist, 39, 90. 
Terraqueous stage, 12. 

Earth in, 12, 13. 
Terrestrial stage, 12; Mars in, 12. 
Tertiary era, 71, 

Thirst, planetary mode of death, 207. 
Tibetan table-lands, 

effect on climate, 99. 
Tidal effects. Notes 270. 
Tokio, size of, 214. 
Trees, deciduous, 

first appearance of, 71. 
Triassic period, 

(new red sandstone), 70, 
Trilobites, 45. 
Trivium Charontis, 149. 
Tropic of Cancer, 125. 
Tropic of Capricorn, 125. 


short on Mars, 


Upper Silurian era, 
insects found in, 46. 

Variation, spontaneous, 

the motive principle of life, 53. 

each planet sets a different stage for, 
Vegetal life, 

effect of plateaux upon, 99, 102. 

blue-green and ochre color suggest 
it, 106. 

on peaks, 103. 
Vegetal quickening, 177. 

luxuriance of, in paleozoic times, 51. 

explains behavior of canals, 177. 

sprouting time, on Earth, 180. 

speed of, 181. 

spread of, 181. 

sprouting time on Mars, 182. 
Venus, 178. 

markings on, 192-193. 

rotary retardation of, 207. 

visibUity of fine lines. Notes 269-279. 
Vernal quickening, 178. 
Very, Professor, 87, 88, Notes 242, 243. 
Vogel, 138. 
Volcanic phenomena, 

proportional to mass of planet, 16. 

occur where crust is most permeable, 


in proportion to mass of planet, 31. 

essential to life, 39. 

boiling points of, on Earth and Mars, 
39, Notes 231-232. 

specific heat of, 51. 

relative amounts on Earth and Mars, 

the answer to the riddle, 198-203. 

of polar caps, 204. 

loss of supply, 208. 

in the air of Mars, 103, 135, 139. 

effect on spectrum. Notes 248. 

Year, length of Martian, 78. 
Zones, area of, 163. 



Director of the Observatory at Flagstaff, Arizona; Non- Resident Professor of Astronomy at 
the Massachusetts Institute of Technology; Fellow of the American Academy of Arts and 
Sciences; Membre de la Soci^te Astronomique de France; Member of the Astronomical 
and Astro-Physical Society of America; Mitglied der Astronomische Gesellschaft; Membre 
de la Societe Beige d'Astronomie; Honorary Member of the Sociedad Astronomica de 
Mexico; Janssen Medalist of the Socidt^ Astronomique de France, 1904, for Researches on 
Mars; etc., etc. 

Cloth, 8vo, illustrated, -$2.^0 net; by mail, $2.'j^ 

" The question whether Mars is inhabited has not been taken up very seriously by 
the great body of astronomers. . . . The latest, and we are inclined to think the fullest 
and best, contribution to its solution is this remarkable volume, written in a very clear 
style, free from scientific technicalities, and illustrated by maps and diagrams, so that 
the non-expert layman can understand it. . . . Mr. Lowell's investigations, coupled 
wi|h those of other earlier investigators, indicate that the inhabitants of Mars are 
carrying on a system of irrigation for agricultural purposes on an immeasurably larger 
scale than has ever been dreamed of on our planet, that they possess a high degree of 
agricultural and mechanical intelligence, and a degree of moral development so far in 
advance of any we have yet reached that in all probability war is among them wholly 
unknown." — Outlook. 

" The book makes fascinating reading, and is intended for the average man of 
intelligence and scientific curiosity. It represents mature reflection, patient investiga- 
tion and observation, and eleven years' additional work and verification. ... It is 
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. . . The book is full of quotable sayings and delightful things. . . . We have here 
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" Mr. Lowell's book embodies such a wealth of observation and reasoning that it is 
not possible to do it justice within the space of the present review. How widely soever 
one may dissent from his conclusions, one must concede that among all the observers 
of the planet, he easily takes first place, both with respect to the favorable conditions 
under which he has worked, the energy and enthusiasm which he has displayed, and 
the care he has taken to avoid every source of error. The most adverse critic cannot 
but admire the tireless industry with which the planet has been scanned night after 
night, every noteworthy appearance regarded, and the mass of facts thus acquired 
moulded into a consistent whole. , . . There is no heavenly body, except the sun, in 
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with his racy, epigrammatic brilliancy of style, his delicate, quiet humor, his daring 
scientific imagination — all held in check by instinctive modesty of good breeding, 
gayly throwing to the winds all professional airs and mere rhetorical bounce — his 
course will be no doubt as charming to the end as it has been steadily illuminating 
even for the illuminati." — Boston Transcript. 





With its applications to the determinati^H and reduction of positions of the fixed stars 


Cloth 8vo $3.00 net 



Chapter I. Introductory. Notes and References. 

Chapter II. Differences, Interpolation, and Development. Notes 
AND References. 

Chapter III. The Method of Least Squares. Section I. Mean Values of 
Quantities. II. Determination of Probable Errors. III. Equations of Condi- 
tion. Notes and References. 


Chapter IV. Spherical Coordinates. Section I. General Theory. II. Prob- 
lems and Applications of the Theory of Spherical Coordinates. 

Chapter V. The Measure of Time and Related Problems. Section I. 
Solar and Sidereal Time. II. The General Measure of Time. III. Problems 
Involving Time. 

Chapter VI. Parallax and Related Subjects. Section I. Figure and 
Dimensions of the Earth. II. Parallax and Semi-diameter. 

Chapter VII. Aberration. 

Chapter VIII. Astronomical Refraction. Section I. The Atmosphere as a 
Refracting Medium. II. Elementary Exposition of Atmospheric Refraction. 
III. General Investigation of Astronomical Refraction. Notes and Refer- 
ences TO Refraction, 

Chapter IX. Precession and Nutation. Section I. Lavi^s of the Precessional 
Motion, II. Relative Positions of the Equator and Equinox at Widely Sepa- 
rated Epochs. III. Nutation. Notes and References to Precession 
AND Nutation. 



Chapter X. Reduction of Mean Places of the Fixed Stars from one 
Epoch to Another. Section I. The Proper Motions of the Stars. II. Trig- 
onometric Reduction for Precession, III. Development of the Coordinates in 
the Powers of the Time. NOTES and References, 

Chapter XI. Reduction to Apparent Place. Section I. Reduction to Terms 
of the First Order. II, Rigorous Reduction for Close Polar Stars, III. Prac- 
tical Methods of Reduction. IV. Construction of Tables of the Apparent Places 
of Fundamental Stars. NOTES AND REFERENCES. 

Chapter XII. Method of Determining the Positions of Stars by Merid- 
ian Observations. Section I. Method of Determining Right Ascensions. 
II. The Determination of Declinations. 

Chapter XIII. Methods of Deriving the Positions and Proper Motions 
of the Stars from Published Results of Observations. Section I. 
Historical Review. II. Reduction of Catalogue Positions of Stars to a Homo- 
geneous System. III. Methods of Combining Star Catalogues. 


List of Independent Star Catalogues. 

Catalogues made at Northern Observatories. 

Catalogues made at Tropical and Southern Observatories. 


Explanation of the Tables of the Appendix. — I. Constants and Formulae 
in Frequent Use. II, Tables Relating to Time and Arguments for Star Reduc- 
tions. Ill, Centennial Rates of the Precessional Motions. IV. Tables and 
Formulas for the Trigonometric Reduction of Mean Places of Stars. V. Reduc- 
tion of the Struve-Peters Precessions to the Adopted Values. VI. Conversion 
of Longitude and Latitude into R. A. and Dec. VII. Refractions. VIII. Co- 
efficients of Solar and Lunar Nutation. IX. Three-place Logarithms and 
Trigonometrical Functions, 

THE MACMILLAN COMPANY, 64-66 Fifth Avenue, New York 





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